Method for synchronizing DU transmission timings of IAB nodes

ABSTRACT

The present specification presents a method for synchronizing DU transmission timings of IAB nodes.

CROSS-REFERENCE TO RELATED APPLICATIONS

Pursuant to 35 U.S.C. § 119(e), this application is a continuation ofInternational Application PCT/KR2020/010800, with an internationalfiling date of Aug. 13, 2020, which claims the benefit of Korean PatentApplication No. 10-2019-0099378, filed on Aug. 14, 2019, Korean PatentApplication No. 10-2019-0106152, filed on Aug. 28, 2019, U.S.Provisional Application No. 62/893,211, filed on Aug. 29, 2019, and U.S.Provisional Application No. 62/915,007, filed on Oct. 14, 2019, thecontents of which are hereby incorporated by reference herein in theirentirety.

BACKGROUND OF THE DISCLOSURE Field of the Disclosure

The present disclosure relates to wireless communication.

Related Art

One potential technology intended to enable future cellular networkdeployment scenarios and applications is supporting wireless backhauland relay links, which enables a flexible and highly dense deployment ofNR cells without needing to proportionally densify a transport network.It allows for flexible and very dense deployment.

With massive MIMO or a native deployment of multi-beam system, a greaterbandwidth (e.g., mmWave spectrum) is expected to be available in NR thanin LTE, and thus occasions for the development and deployment ofintegrated access and backhaul links arise. This allows an easydeployment of a dense network of self-backhauled NR cells in anintegrated manner by establishing a plurality of control and datachannels/procedures defined to provide connection or access to UEs. Thissystem is referred to as an integrated access and backhaul (IAB) link.

In a multi-hop IAB system in which multiple IAB nodes are connected, thetime domain synchronization becomes a problem to perform smoothcommunication between IAB nodes.

SUMMARY

The present disclosure proposes a synchronization method for a DUtransmission timing of an IAB node.

Advantageous Effects

According to the present disclosure, a synchronization method for a DUtransmission timing of an IAB node is proposed, and through this, timedomain synchronization between IAB nodes is performed, and accordingly,communication efficiency is improved.

The effects that can be obtained through specific examples of thepresent disclosure are not limited to the effects listed above. Forexample, there may be various technical effects that a person havingordinary skill in the related art can understand or derive from thepresent disclosure. Accordingly, specific effects of the presentdisclosure are not limited to those explicitly described in the presentdisclosure and may include various effects that can be understood orderived from the technical features of the present disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a wireless communication system to which the presentdisclosure may be applied.

FIG. 2 is a diagram showing a wireless protocol architecture for a userplane.

FIG. 3 is a diagram showing a wireless protocol architecture for acontrol plane.

FIG. 4 shows another wireless communication system to which the presentdisclosure may be applied.

FIG. 5 illustrates a functional division between an NG-RAN and a 5GC.

FIG. 6 illustrates an example of a frame structure that may be appliedin NR.

FIG. 7 illustrates a slot structure.

FIG. 8 illustrates CORESET.

FIG. 9 is a diagram illustrating a difference between a related artcontrol region and the CORESET in NR.

FIG. 10 illustrates an example of a frame structure for new radio accesstechnology.

FIG. 11 illustrates a structure of a self-contained slot.

FIG. 12 is an abstract schematic diagram illustrating hybrid beamformingfrom the viewpoint of TXRUs and physical antennas.

FIG. 13 schematically illustrates a synchronization signal/PBCH(SS/PBCH) block.

FIG. 14 illustrates a method for a UE to obtain timing information.

FIG. 15 illustrates an example of a system information acquisitionprocess of a UE.

FIG. 16 illustrates a random access procedure.

FIG. 17 illustrates a power ramping counter.

FIG. 18 illustrates the concept of the threshold of an SS block in arelationship with an RACH resource.

FIG. 19 is a flowchart illustrating an example of performing anidle-mode DRX operation.

FIG. 20 illustrates a DRX cycle.

FIG. 21 schematically illustrates an example of a network having anintegrated access and backhaul (IAB) link.

FIG. 22 shows an example of an operation of the IAB system in astandalone (SA) mode and a non-standalone (NSA) mode.

FIG. 23 schematically illustrates an example of the configuration ofaccess and backhaul links.

FIG. 24 illustrates a link and relationship between IAB nodes.

FIG. 25 is a diagram illustrating an example of a downlinktransmission/reception operation.

FIG. 26 is a diagram illustrating an example of an uplinktransmission/reception operation.

FIG. 27 shows an example of an uplink grant.

FIG. 28 is a diagram illustrating an example of a grant-free initialtransmission.

FIG. 29 shows an example of a conceptual diagram of uplink physicalchannel processing.

FIG. 30 shows an example of an NR slot in which a PUCCH is transmitted.

FIG. 31 is a diagram illustrating an example of the HARQ-ACK timing(K1).

FIG. 32 illustrates an MT configuration and a DU configuration.

FIG. 33 shows an example of timing alignment in TDD based on theproposed methods of the present disclosure.

FIG. 34 is a flowchart of an example of a method for updating an X valuebased on Proposed Method 1.

FIG. 35 shows an example to which the proposed method 1-1 is applied.

FIG. 36 is a diagram for an example of an operation between a parentnode and a child node based on the proposed method 2.

FIG. 37 is a flowchart for an example of a synchronization method for aDU transmission timing performed by an IAB node according to someimplementations of the present disclosure.

FIG. 38 is illustrated to describe the random access procedure.

FIG. 39 illustrates a communication system 1 applied to the disclosure.

FIG. 40 illustrates a wireless device that is applicable to thedisclosure.

FIG. 41 illustrates a signal processing circuit for a transmissionsignal.

FIG. 42 illustrates another example of a wireless device applied to thedisclosure.

FIG. 43 illustrates a hand-held device applied to the disclosure.

FIG. 44 illustrates a vehicle or an autonomous driving vehicle appliedto the disclosure.

FIG. 45 illustrates a vehicle applied to the disclosure.

FIG. 46 illustrates a XR device applied to the disclosure.

FIG. 47 illustrates a robot applied to the disclosure.

FIG. 48 illustrates an AI device applied to the disclosure.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

As used herein, “A or B” may mean “only A”, “only B”, or “both A and B”.That is, “A or B” may be interpreted as “A and/or B” herein. Forexample, “A, B or C” may mean “only A”, “only B”, “only C”, or “anycombination of A, B, and C”.

As used herein, a slash (/) or a comma (,) may mean “and/or”. Forexample, “A/B” may mean “A and/or B”. Therefore, “A/B” may include “onlyA”, “only B”, or “both A and B”. For example, “A, B, C” may mean “A, B,or C”.

As used herein, “at least one of A and B” may mean “only A”, “only B”,or “both A and B”. Further, as used herein, “at least one of A or B” or“at least one of A and/or B” may be interpreted equally as “at least oneof A and B”.

As used herein, “at least one of A, B, and C” may mean “only A”, “onlyB”, “only C”, or “any combination of A, B, and C”. Further, “at leastone of A, B, or C” or “at least one of A, B, and/or C” may mean “atleast one of A, B, and C”.

As used herein, parentheses may mean “for example”. For instance, theexpression “control information (PDCCH)” may mean that a PDCCH isproposed as an example of control information. That is, controlinformation is not limited to a PDCCH, but a PDCCH is proposed as anexample of control information. Further, the expression “controlinformation (i.e., a PDCCH)” may also mean that a PDCCH is proposed asan example of control information.

Technical features that are separately described in one drawing may beimplemented separately or may be implemented simultaneously.

FIG. 1 shows a wireless communication system to which the presentdisclosure may be applied. The wireless communication system may bereferred to as an Evolved-UMTS Terrestrial Radio Access Network(E-UTRAN) or a Long Term Evolution (LTE)/LTE-A system.

The E-UTRAN includes at least one base station (BS) 20 which provides acontrol plane and a user plane to a user equipment (UE) 10. The UE 10may be fixed or mobile, and may be referred to as another terminology,such as a mobile station (MS), a user terminal (UT), a subscriberstation (SS), a mobile terminal (MT), a wireless device, etc. The BS 20is generally a fixed station that communicates with the UE 10 and may bereferred to as another terminology, such as an evolved node-B (eNB), abase transceiver system (BTS), an access point, etc.

The BSs 20 are interconnected by means of an X2 interface. The BSs 20are also connected by means of an S1 interface to an evolved packet core(EPC) 30, more specifically, to a mobility management entity (MME)through S1-MME and to a serving gateway (S-GW) through S1-U.

The EPC 30 includes an MME, an S-GW, and a packet data network-gateway(P-GW). The MME has access information of the UE or capabilityinformation of the UE, and such information is generally used formobility management of the UE. The S-GW is a gateway having an E-UTRANas an end point. The P-GW is a gateway having a PDN as an end point.

Layers of a radio interface protocol between the UE and the network canbe classified into a first layer (L1), a second layer (L2), and a thirdlayer (L3) based on the lower three layers of the open systeminterconnection (OSI) model that is well-known in the communicationsystem. Among them, a physical (PHY) layer belonging to the first layerprovides an information transfer service by using a physical channel,and a radio resource control (RRC) layer belonging to the third layerserves to control a radio resource between the UE and the network. Forthis, the RRC layer exchanges an RRC message between the UE and the BS.

FIG. 2 is a diagram showing a wireless protocol architecture for a userplane. FIG. 3 is a diagram showing a wireless protocol architecture fora control plane. The user plane is a protocol stack for user datatransmission. The control plane is a protocol stack for control signaltransmission.

Referring to FIGS. 2 and 3, a PHY layer provides an upper layer with aninformation transfer service through a physical channel. The PHY layeris connected to a medium access control (MAC) layer which is an upperlayer of the PHY layer through a transport channel. Data is transferredbetween the MAC layer and the PHY layer through the transport channel.The transport channel is classified according to how and with whatcharacteristics data is transferred through a radio interface.

Data is moved between different PHY layers, that is, the PHY layers of atransmitter and a receiver, through a physical channel. The physicalchannel may be modulated according to an Orthogonal Frequency DivisionMultiplexing (OFDM) scheme, and use the time and frequency as radioresources.

The functions of the MAC layer include mapping between a logical channeland a transport channel and multiplexing and demultiplexing to atransport block that is provided through a physical channel on thetransport channel of a MAC Service Data Unit (SDU) that belongs to alogical channel. The MAC layer provides service to a Radio Link Control(RLC) layer through the logical channel.

The functions of the RLC layer include the concatenation, segmentation,and reassembly of an RLC SDU. In order to guarantee various types ofQuality of Service (QoS) required by a Radio Bearer (RB), the RLC layerprovides three types of operation mode: Transparent Mode (TM),Unacknowledged Mode (UM), and Acknowledged Mode (AM). AM RLC provideserror correction through an Automatic Repeat Request (ARQ).

The RRC layer is defined only on the control plane. The RRC layer isrelated to the configuration, reconfiguration, and release of radiobearers, and is responsible for control of logical channels, transportchannels, and PHY channels. An RB means a logical route that is providedby the first layer (PHY layer) and the second layers (MAC layer, the RLClayer, and the PDCP layer) in order to transfer data between UE and anetwork.

The function of a Packet Data Convergence Protocol (PDCP) layer on theuser plane includes the transfer of user data and header compression andciphering. The function of the PDCP layer on the user plane furtherincludes the transfer and encryption/integrity protection of controlplane data.

What an RB is configured means a process of defining the characteristicsof a wireless protocol layer and channels in order to provide specificservice and configuring each detailed parameter and operating method. AnRB can be divided into two types of a Signaling RB (SRB) and a Data RB(DRB). The SRB is used as a passage through which an RRC message istransmitted on the control plane, and the DRB is used as a passagethrough which user data is transmitted on the user plane.

If RRC connection is established between the RRC layer of UE and the RRClayer of an E-UTRAN, the UE is in the RRC connected state. If not, theUE is in the RRC idle state.

A downlink transport channel through which data is transmitted from anetwork to UE includes a broadcast channel (BCH) through which systeminformation is transmitted and a downlink shared channel (SCH) throughwhich user traffic or control messages are transmitted. Traffic or acontrol message for downlink multicast or broadcast service may betransmitted through the downlink SCH, or may be transmitted through anadditional downlink multicast channel (MCH). Meanwhile, an uplinktransport channel through which data is transmitted from UE to a networkincludes a random access channel (RACH) through which an initial controlmessage is transmitted and an uplink shared channel (SCH) through whichuser traffic or control messages are transmitted.

Logical channels that are placed over the transport channel and that aremapped to the transport channel include a broadcast control channel(BCCH), a paging control channel (PCCH), a common control channel(CCCH), a multicast control channel (MCCH), and a multicast trafficchannel (MTCH).

The physical channel includes several OFDM symbols in the time domainand several subcarriers in the frequency domain. One subframe includes aplurality of OFDM symbols in the time domain. An RB is a resourcesallocation unit, and includes a plurality of OFDM symbols and aplurality of subcarriers. Furthermore, each subframe may use specificsubcarriers of specific OFDM symbols (e.g., the first OFDM symbol) ofthe corresponding subframe for a physical downlink control channel(PDCCH), that is, an L1/L2 control channel. A Transmission Time Interval(TTI) is a unit time for transmission, e.g., a subframe or a slot.

Hereinafter, a new radio access technology (new RAT, NR) will bedescribed.

As more and more communication devices require more communicationcapacity, there is a need for improved mobile broadband communicationover existing radio access technology. Also, massive machine typecommunications (MTC), which provides various services by connecting manydevices and objects, is one of the major issues to be considered in thenext generation communication. In addition, communication system designconsidering reliability/latency sensitive service/UE is being discussed.The introduction of next generation radio access technology consideringenhanced mobile broadband communication (eMBB), massive MTC (mMTC),ultrareliable and low latency communication (URLLC) is discussed. Thisnew technology may be called new radio access technology (new RAT or NR)in the present disclosure for convenience.

FIG. 4 shows another wireless communication system to which the presentdisclosure may be applied.

Specifically, FIG. 4 shows a system architecture based on a 5G new radioaccess technology (NR) system. An entity used in the 5G NR system(hereinafter, simply referred to as “NR”) may absorb some or allfunctions of the entity (e.g., eNB, MME, S-GW) introduced in FIG. 1(e.g., eNB, MME, S-GW). The entity used in the NR system may beidentified in the name of “NG” to distinguish it from LTE.

Referring to FIG. 4, a wireless communication system includes one ormore UEs 11, a next-generation RAN (NG-RAN), and a 5th generation corenetwork (5GC). The NG-RAN consists of at least one NG-RAN node. TheNG-RAN node is an entity corresponding to the BS 20 of FIG. 1. TheNG-RAN node consists of at least one gNB 21 and/or at least one ng-eNB22. The gNB 21 provides NR user plane and control plane protocolterminations towards the UE 11. The Ng-eNB 22 provides an E-UTRA userplane and control plane protocol terminations towards the UE 11.

The 5GC includes an access and mobility management function (AMF), auser plane function (UPF), and a session management function (SMF). TheAMF hosts functions, such as non-access stratum (NAS) security, idlestate mobility processing, and so on. The AMF is an entity including theconventional MMF function. The UPF hosts functions, such as mobilityanchoring, protocol data unit (PDU) processing, and so on. The UPF is anentity including the conventional S-GW function. The SMF hostsfunctions, such as UE Internet Protocol (IP) address allocation, PDUsession control, and so on.

The gNB and the ng-eNB are interconnected through an Xn interface. ThegNB and the ng-eNB are also connected to the 5GC through an NGinterface. More specifically, the gNB and the ng-eNB are connected tothe AMF through an NG-C interface, and are connected to the UPF throughan NG-U interface.

FIG. 5 illustrates a functional division between an NG-RAN and a 5GC.

Referring to FIG. 5, the gNB may provide functions such as an inter-cellradio resource management (Inter Cell RRM), radio bearer management (RBcontrol), connection mobility control, radio admission control,measurement configuration & provision, dynamic resource allocation, andthe like. The AMF may provide functions such as NAS security, idle statemobility handling, and so on. The UPF may provide functions such asmobility anchoring, PDU processing, and the like. The SMF may providefunctions such as UE IP address assignment, PDU session control, and soon.

FIG. 6 illustrates an example of a frame structure that may be appliedin NR.

Referring to FIG. 6, a frame may be composed of 10 milliseconds (ms) andinclude 10 subframes each composed of 1 ms.

In the NR, uplink and downlink transmissions may be configured on aframe basis. A radio frame has a length of 10 ms, and may be defined astwo 5 ms half-frames (HFs). The HF may be defined as five 1 mssub-frames (SFs). The SF is divided into one or more slots, and thenumber of slots in the SF depends on a subcarrier spacing (SCS). Eachslot includes 12 or 14 OFDM(A) symbols according to a cyclic prefix(CP). When a normal CP is used, each slot includes 14 symbols. When anextended CP is used, each slot includes 12 symbols. Herein, the symbolmay include an OFDM symbol (or CP-OFDM symbol) and an SC-FDMA symbol (orDFT-S-OFDM symbol).

One or a plurality of slots may be included in a subframe according tosubcarrier spacings.

The following table 1 illustrates a subcarrier spacing configuration μ.

TABLE 1 μ Δf = 2^(μ) · 15[kHz] Cyclic prefix 0 15 Normal 1 30 Normal 260 Normal Extended 3 120 Normal 4 240 Normal

The following table 2 illustrates the number of slots in a frame(N^(frame,μ) _(slot)), the number of slots in a subframe (N^(subframe,μ)_(slot)), the number of symbols in a slot (N^(slot) _(symb)), and thelike, according to subcarrier spacing configurations

TABLE 2 μ N_(symb) ^(slot) N_(slot) ^(frame,μ) N_(slot) ^(subframe,μ) 014 10 1 1 14 20 2 2 14 40 4 3 14 80 8 4 14 160 16

Table 3 below illustrates that the number of symbols per slot, thenumber of slots per frame, and the number of slots per subframe varydepending on the SCS, in case of using an extended CP.

TABLE 3 SCS(15*2{circumflex over ( )} μ) N^(slot) _(symb) N^(frame,u)_(slot) N^(subframe,u) _(slot) 60 KHz (μ = 2) 12 40 4NR supports multiple numbers (or subcarrier spacing (SCS)) to supportvarious 5G services. For example, when the SCS is 15 kHz, a wide regionin the legacy cellular band is supported; and when the SCS is 30 kHz/60kHz, dense urban areas, low time delay and wide carrier bandwidth aresupported; and when the SCS is 60 kHz or more, a bandwidth of more than24.25 GHz is supported in order to overcome phase noise.

The NR frequency band may be defined as two types of frequency ranges(FR1 and FR2). A numerical value of the frequency range may be changedand, for example, the two types of frequency ranges (FR1 and FR2) may beas shown in Table 4 below. For convenience of explanation, among thefrequency ranges used in the NR system, FR1 may refer to “sub 6 GHzrange” and FR2 may refer to “above 6 GHz range” and may be calledmillimeter wave (mmW).

TABLE 4 Frequency Range Corresponding frequency designation rangeSubcarrier Spacing FR1  450 MHz-6000 MHz 15, 30, 60 kHz FR2 24250MHz-52600 MHz 60, 120, 240 kHz

As described above, the numerical value of the frequency range of the NRsystem may be changed. For example, FR1 may include a band of 410 MHz to7125 MHz as shown in Table 5 below. That is, FR1 may include a frequencyband of 6 GHz (or 5850, 5900, 5925 MHz, etc.) or higher. For example,the frequency band of 6 GHz (or 5850, 5900, 5925 MHz, etc.) or higherincluded in FR1 may include an unlicensed band. The unlicensed band maybe used for various purposes, for example, for communication for avehicle (e.g., autonomous driving).

TABLE 5 Frequency Range Corresponding frequency designation rangeSubcarrier Spacing FR1  410 MHz-7125 MHz 15, 30, 60 kHz FR2 24250MHz-52600 MHz 60, 120, 240 kHz

In an NR system, OFDM(A) numerologies (e.g., SCS, CP length, and so on)may be differently configured between a plurality of cells integrated toone UE. Accordingly, an (absolute time) duration of a time resource(e.g., SF, slot or TTI) (for convenience, collectively referred to as atime unit (TU)) configured of the same number of symbols may bedifferently configured between the integrated cells.

FIG. 7 illustrates a slot structure.

Referring to FIG. 7, a slot includes a plurality of symbols in a timedomain. For example, in case of a normal CP, one slot may include 14symbols. However, in case of an extended CP, one slot may include 12symbols. Alternatively, in case of the normal CP, one slot may include 7symbols. However, in case of the extended CP, one slot may include 6symbols.

A carrier includes a plurality of subcarriers in a frequency domain. Aresource block (RB) may be defined as a plurality of consecutivesubcarriers (e.g., 12 subcarriers) in the frequency domain. A bandwidthpart (BWP) may be defined as a plurality of consecutive (P)RBs in thefrequency domain, and the BWP may correspond to one numerology (e.g.,SCS, CP length, and so on). The carrier ma include up to N (e.g., 5)BWPs. Data communication may be performed through an activated BWP. Eachelement may be referred to as a resource element (RE) within a resourcegrid, and one complex symbol may be mapped thereto.

A physical downlink control channel (PDCCH) may include one or morecontrol channel elements (CCEs) as illustrated in the following table 6.

TABLE 6 Aggregation level Number of CCEs 1 1 2 2 4 4 8 8 16 16

That is, the PDCCH may be transmitted through a resource including 1, 2,4, 8, or 16 CCEs. Here, the CCE includes six resource element groups(REGs), and one REG includes one resource block in a frequency domainand one orthogonal frequency division multiplexing (OFDM) symbol in atime domain.

A new unit called a control resource set (CORESET) may be introduced inthe NR. The UE may receive a PDCCH in the CORESET.

FIG. 8 illustrates CORESET.

Referring to FIG. 8, the CORESET includes N^(CORESET) _(RB) number ofresource blocks in the frequency domain, and N^(CORESET) _(symb)∈{1, 2,3} number of symbols in the time domain. N^(CORESET) _(RB) andN^(CORESET) _(symb) may be provided by a base station via higher layersignaling. As illustrated in FIG. 8, a plurality of CCEs (or REGs) maybe included in the CORESET.

The UE may attempt to detect a PDCCH in units of 1, 2, 4, 8, or 16 CCEsin the CORESET. One or a plurality of CCEs in which PDCCH detection maybe attempted may be referred to as PDCCH candidates.

A plurality of CORESETs may be configured for the terminal.

FIG. 9 is a diagram illustrating a difference between a related artcontrol region and the CORESET in NR.

Referring to FIG. 9, a control region 300 in the related art wirelesscommunication system (e.g., LTE/LTE-A) is configured over the entiresystem band used by a base station (BS). All the terminals, excludingsome (e.g., eMTC/NB-IoT terminal) supporting only a narrow band, must beable to receive wireless signals of the entire system band of the BS inorder to properly receive/decode control information transmitted by theBS.

On the other hand, in NR, CORESET described above was introduced.CORESETs 301, 302, and 303 are radio resources for control informationto be received by the terminal and may use only a portion, rather thanthe entirety of the system bandwidth. The BS may allocate the CORESET toeach UE and may transmit control information through the allocatedCORESET. For example, in FIG. 9, a first CORESET 301 may be allocated toUE 1, a second CORESET 302 may be allocated to UE 2, and a third CORESET303 may be allocated to UE 3. In the NR, the terminal may receivecontrol information from the BS, without necessarily receiving theentire system band.

The CORESET may include a UE-specific CORESET for transmittingUE-specific control information and a common CORESET for transmittingcontrol information common to all UEs.

Meanwhile, NR may require high reliability according to applications. Insuch a situation, a target block error rate (BLER) for downlink controlinformation (DCI) transmitted through a downlink control channel (e.g.,physical downlink control channel (PDCCH)) may remarkably decreasecompared to those of conventional technologies. As an example of amethod for satisfying requirement that requires high reliability,content included in DCI can be reduced and/or the amount of resourcesused for DCI transmission can be increased. Here, resources can includeat least one of resources in the time domain, resources in the frequencydomain, resources in the code domain and resources in the spatialdomain.

In NR, the following technologies/features can be applied.

<Self-Contained Subframe Structure>

FIG. 10 illustrates an example of a frame structure for new radio accesstechnology.

In NR, a structure in which a control channel and a data channel aretime-division-multiplexed within one TTI, as shown in FIG. 10, can beconsidered as a frame structure in order to minimize latency.

In FIG. 10, a shaded region represents a downlink control region and ablack region represents an uplink control region. The remaining regionmay be used for downlink (DL) data transmission or uplink (UL) datatransmission. This structure is characterized in that DL transmissionand UL transmission are sequentially performed within one subframe andthus DL data can be transmitted and UL ACK/NACK can be received withinthe subframe. Consequently, a time required from occurrence of a datatransmission error to data retransmission is reduced, thereby minimizinglatency in final data transmission.

In this data and control TDMed subframe structure, a time gap for a basestation and a terminal to switch from a transmission mode to a receptionmode or from the reception mode to the transmission mode may berequired. To this end, some OFDM symbols at a time when DL switches toUL may be set to a guard period (GP) in the self-contained subframestructure.

FIG. 11 illustrates a structure of a self-contained slot.

In an NR system, a DL control channel, DL or UL data, a UL controlchannel, and the like may be contained in one slot. For example, first Nsymbols (hereinafter, DL control region) in the slot may be used totransmit a DL control channel, and last M symbols (hereinafter, ULcontrol region) in the slot may be used to transmit a UL controlchannel. N and M are integers greater than or equal to 0. A resourceregion (hereinafter, a data region) which exists between the DL controlregion and the UL control region may be used for DL data transmission orUL data transmission. For example, the following configuration may beconsidered. Respective durations are listed in a temporal order.

1. DL only configuration

2. UL only configuration

3. Mixed UL-DL configuration

-   -   DL region+Guard period (GP)+UL control region    -   DL control region+GP+UL region

Here, DL region may be (i) DL data region, (ii) DL control region+DLdata region. UL region may be (i) UL data region, (ii) UL data region+ULcontrol region.

A PDCCH may be transmitted in the DL control region, and a physicaldownlink shared channel (PDSCH) may be transmitted in the DL dataregion. A physical uplink control channel (PUCCH) may be transmitted inthe UL control region, and a physical uplink shared channel (PUSCH) maybe transmitted in the UL data region. Downlink control information(DCI), for example, DL data scheduling information, UL data schedulinginformation, and the like, may be transmitted on the PDCCH. Uplinkcontrol information (UCI), for example, ACK/NACK information about DLdata, channel state information (CSI), and a scheduling request (SR),may be transmitted on the PUCCH. A GP provides a time gap in a processin which a BS and a UE switch from a TX mode to an RX mode or a processin which the BS and the UE switch from the RX mode to the TX mode. Somesymbols at the time of switching from DL to UL within a subframe may beconfigured as the GP.

<Analog Beamforming #1>

Wavelengths are shortened in millimeter wave (mmW) and thus a largenumber of antenna elements can be installed in the same area. That is,the wavelength is 1 cm at 30 GHz and thus a total of 100 antennaelements can be installed in the form of a 2-dimensional array at aninterval of 0.5 lambda (wavelength) in a panel of 5×5 cm. Accordingly,it is possible to increase a beamforming (BF) gain using a large numberof antenna elements to increase coverage or improve throughput in mmW.

In this case, if a transceiver unit (TXRU) is provided to adjusttransmission power and phase per antenna element, independentbeamforming per frequency resource can be performed. However,installation of TXRUs for all of about 100 antenna elements decreaseseffectiveness in terms of cost. Accordingly, a method of mapping a largenumber of antenna elements to one TXRU and controlling a beam directionusing an analog phase shifter is considered. Such analog beamforming canform only one beam direction in all bands and thus cannot providefrequency selective beamforming.

Hybrid beamforming (BF) having a number B of TXRUs which is smaller thanQ antenna elements can be considered as an intermediate form of digitalBF and analog BF. In this case, the number of directions of beams whichcan be simultaneously transmitted are limited to B although it dependson a method of connecting the B TXRUs and the Q antenna elements.

<Analog Beamforming #2>

When a plurality of antennas is used in NR, hybrid beamforming which isa combination of digital beamforming and analog beamforming is emerging.Here, in analog beamforming (or RF beamforming) an RF end performsprecoding (or combining) and thus it is possible to achieve theperformance similar to digital beamforming while reducing the number ofRF chains and the number of D/A (or A/D) converters. For convenience,the hybrid beamforming structure may be represented by N TXRUs and Mphysical antennas. Then, the digital beamforming for the L data layersto be transmitted at the transmitting end may be represented by an N byL matrix, and the converted N digital signals are converted into analogsignals via TXRUs, and analog beamforming represented by an M by Nmatrix is applied.

FIG. 12 is an abstract schematic diagram illustrating hybrid beamformingfrom the viewpoint of TXRUs and physical antennas.

In FIG. 12, the number of digital beams is L and the number of analogbeams is N. Further, in the NR system, by designing the base station tochange the analog beamforming in units of symbols, it is considered tosupport more efficient beamforming for a terminal located in a specificarea. Furthermore, when defining N TXRUs and M RF antennas as oneantenna panel in FIG. 12, it is considered to introduce a plurality ofantenna panels to which independent hybrid beamforming is applicable inthe NR system.

When a base station uses a plurality of analog beams as described above,analog beams suitable to receive signals may be different for terminalsand thus a beam sweeping operation of sweeping a plurality of analogbeams to be applied by a base station per symbol in a specific subframe(SF) for at least a synchronization signal, system information andpaging such that all terminals can have reception opportunities isconsidered.

FIG. 13 schematically illustrates a synchronization signal/PBCH(SS/PBCH) block.

Referring to FIG. 13, an SS/PBCH block may include a PSS and an SSS,each of which occupies one symbol and 127 subcarriers, and a PBCH, whichspans three OFDM symbols and 240 subcarriers where one symbol mayinclude an unoccupied portion in the middle reserved for the SSS. Theperiodicity of the SS/PBCH block may be configured by a network, and atime position for transmitting the SS/PBCH block may be determined onthe basis of subcarrier spacing.

Polar coding may be used for the PBCH. A UE may assume band-specificsubcarrier spacing for the SS/PBCH block as long as a network does notconfigure the UE to assume different subcarrier spacings.

The PBCH symbols carry frequency-multiplexed DMRS thereof. QPSK may beused for the PBCH. 1008 unique physical-layer cell IDs may be assigned.

Regarding a half frame having SS/PBCH blocks, the indexes of firstsymbols of candidate SS/PBCH blocks are determined according to thesubcarrier spacing of SS/PBCH blocks described blow.

Case A—Subcarrier spacing of 15 kHz: The first symbols of the candidateSS/PBCH blocks have an index represented by {2, 8}+14*n where n=0, 1 fora carrier frequency of 3 GHz or less and n=0, 1, 2, 3 for a carrierfrequency which is greater than 3 GHz and is less than or equal to 6GHz.

Case B—Subcarrier spacing of 30 kHz: The first symbols of the candidateSS/PBCH blocks have an index represented by {4, 8, 16, 20}+28*n wheren=0 for a carrier frequency of 3 GHz or less and n=0, 1 for a carrierfrequency which is greater than 3 GHz and is less than or equal to 6GHz.

Case C—Subcarrier spacing of 30 kHz: The first symbols of the candidateSS/PBCH blocks have an index represented by {2, 8}+14*n where n=0, 1 fora carrier frequency of 3 GHz or less and n=0, 1, 2, 3 for a carrierfrequency which is greater than 3 GHz and is less than or equal to 6GHz.

Case D—Subcarrier spacing of 120 kHz: The first symbols of the candidateSS/PBCH blocks have an index represented by {4, 8, 16, 20}+28*n wheren=0, 1, 2, 3, 5, 6, 7, 8, 10, 11, 12, 13, 15, 16, 17, 18 for a carrierfrequency greater than 6 GHz.

Case E—Subcarrier spacing of 240 kHz: The first symbols of the candidateSS/PBCH blocks have an index represented by {8, 12, 16, 20, 32, 36, 40,44}+56*n where n=0, 1, 2, 3, 5, 6, 7, 8 for a carrier frequency greaterthan 6 GHz.

The candidate SS/PBCH blocks in the half frame are indexed in ascendingorder from 0 to L−1 on the time axis. The UE needs to determine two LSBsfor L=4 of the SS/PBCH block index per half frame and three LSBs for L>4from one-to-one mapping with the index of a DM-RS sequence transmittedin the PBCH. For L=64, the UE needs to determine three MSBs of theSS/PBCH block index per half frame by PBCH payload bits.

The indexes of SS/PBCH blocks in which the UE cannot receive othersignals or channels in REs overlapping with REs corresponding to theSS/PBCH blocks may be set via a higher-layer parameter‘SSB-transmitted-SIB1’. Further, the indexes of SS/PBCH blocks perserving cell in which the UE cannot receive other signals or channels inREs overlapping with REs corresponding to the SS/PBCH blocks may be setvia a higher-layer parameter ‘SSB-transmitted’. The setting via‘SSB-transmitted’ may override the setting via ‘SSB-transmitted-SIB1’.The periodicity of a half frame for reception of SS/PBCH blocks perserving cell may be set via a higher-layer parameter‘SSB-periodicityServingCell’. When the UE does not receive the settingof the periodicity of the half frame for the reception of the SS/PBCHblocks, the UE needs to assume the periodicity of the half frame. The UEmay assume that the periodicity is the same for all SS/PBCH blocks in aserving cell.

FIG. 14 illustrates a method for a UE to obtain timing information.

First, a UE may obtain six-bit SFN information through a masterinformation block (MIB) received in a PBCH. Further, the UE may obtain afour-bit SFN in a PBCH transport block.

Second, the UE may obtain a one-bit half frame indicator as part of aPBCH payload. In less than 3 GHz, the half frame indicator may beimplicitly signaled as part of a PBCH DMRS for Lmax=4.

Finally, the UE may obtain an SS/PBCH block index by a DMRS sequence andthe PBCH payload. That is, the UE may obtain three bits of LSB of the SSblock index by the DMRS sequence for a period of 5 ms. Also, three bitsof MSB of timing information are explicitly carried in the PBCH payload(for more than 6 GHz).

In initial cell selection, the UE may assume that a half frame havingSS/PBCH blocks occurs with a periodicity of two frames. Upon detectingan SS/PBCH block, when k_(SSB)≤23 for FR1 and k_(SSB)≤11 for FR2, the UEdetermines that a control resource set for a Type0-PDCCH common searchspace exists. When k_(SSB)>23 for FR1 and k_(SSB)>11 for FR2, the UEdetermines that there is no control resource set for the Type0-PDCCHcommon search space.

For a serving cell in which SS/PBCH blocks are not transmitted, the UEobtains time and frequency synchronization of the serving cell based onreception of SS/PBCH blocks on a PCell or PSCell of a cell group for theserving cell.

Hereinafter, acquisition of system information will be described.

System information (SI) is divided into a master information block (MIB)and a plurality of system information blocks (SIBs) where:

-   -   the MIB is transmitted always on a BCH according to a period of        80 ms, is repeated within 80 ms, and includes parameters        necessary to obtain system information block type1 (SIB1) from a        cell;    -   SIB1 is periodically and repeatedly transmitted on a DL-SCH.        SIB1 includes information on availability and scheduling (e.g.,        periodicity or SI window size) of other SIBs. Further, SIB1        indicates whether the SIBs (i.e., the other SIBs) are        periodically broadcast or are provided by request. When the        other SIBs are provided by request, SIB1 includes information        for a UE to request SI;    -   SIBs other than SIB1 are carried via system information (SI)        messages transmitted on the DL-SCH. Each SI message is        transmitted within a time-domain window (referred to as an SI        window) periodically occurring;    -   For a PSCell and SCells, an RAN provides required SI by        dedicated signaling. Nevertheless, a UE needs to acquire an MIB        of the PSCell in order to obtain the SFN timing of a SCH (which        may be different from an MCG). When relevant SI for a SCell is        changed, the RAN releases and adds the related SCell. For the        PSCell, SI can be changed only by reconfiguration with        synchronization (sync).

FIG. 15 illustrates an example of a system information acquisitionprocess of a UE.

Referring to FIG. 15, the UE may receive an MIB from a network and maythen receive SIB1. Subsequently, the UE may transmit a systeminformation request to the network and may receive a system informationmessage from the network in response.

The UE may apply a system information acquisition procedure foracquiring access stratum (AS) and non-access stratum (NAS) information.

In RRC_IDLE and RRC_INACTIVE states, the UE needs to ensure validversions of (at least) the MIB, SIB1, and system information block typeX (according to relevant RAT support for mobility controlled by the UE).

In an RRC_CONNECTED state, the UE needs to ensure valid versions of theMIB, SIB1, and system information block type X (according to mobilitysupport for relevant RAT).

The UE needs to store relevant SI obtained from a currentlycamping/serving cell. The version of the SI obtained and stored by theUE is valid only for a certain period of time. The UE may use thisversion of the stored SI, for example, after cell reselection, afterreturn from out of coverage, or after indication of a system informationchange.

Hereinafter, random access will be described.

A UE's random access procedure may be summarized in Table 7.

TABLE 7 Type of signal Operation/obtained information Step 1 UplinkPRACH To obtain initial beam preamble Random election of RA-preamble IDStep 2 Random access response Timing alignment information on DL-SCHRA-preamble ID Initial uplink grant, temporary C-RNTI Step 3 Uplinktransmission on RRC connection request UL-SCH UE identifier Step 4Downlink contention C-RNTI on PDCCH for initial access resolution C-RNTIon PDCCH for RRC_CONNECTED UE

FIG. 16 illustrates a random access procedure.

Referring to FIG. 16, first, a UE may transmit a PRACH preamble as Msg 1of the random access procedure via an uplink.

Two random access preamble sequences having different lengths aresupported. A long sequence having a length of 839 is applied to asubcarrier spacing of 1.25 kHz and 5 kHz, and a short sequence having alength of 139 is applied to a subcarrier spacing of 15 kHz, 30 kHz, 60kHz, and 120 kHz. The long sequence supports an unrestricted set andrestricted sets of type A and type B, while the short sequence maysupport only an unrestricted set.

A plurality of RACH preamble formats is defined by one or more RACH OFDMsymbols, different cyclic prefixes (CPs), and a guard time. A PRACHpreamble setting to be used is provided to the UE as system information.

When there is no response to Msg1, the UE may retransmit thepower-ramped PRACH preamble within a specified number of times. The UEcalculates PRACH transmission power for retransmission of the preamblebased on the most recent estimated path loss and a power rampingcounter. When the UE performs beam switching, the power ramping counterdoes not change.

FIG. 17 illustrates a power ramping counter.

A UE may perform power ramping for retransmission of a random accesspreamble based on a power ramping counter. Here, as described above,when the UE performs beam switching in PRACH retransmission, the powerramping counter does not change.

Referring to FIG. 17, when the UE retransmits the random access preamblefor the same beam, the UE increases the power ramping counter by 1, forexample, the power ramping counter is increased from 1 to 2 and from 3to 4. However, when the beam is changed, the power ramping counter doesnot change in PRACH retransmission.

FIG. 18 illustrates the concept of the threshold of an SS block in arelationship with an RACH resource.

A UE knows the relationship between SS blocks and RACH resources throughsystem information. The threshold of an SS block in a relationship withan RACH resource is based on RSRP and a network configuration.Transmission or retransmission of a RACH preamble is based on an SSblock satisfying the threshold. Therefore, in the example of FIG. 18,since SS block m exceeds the threshold of received power, the RACHpreamble is transmitted or retransmitted based on SS block m.

Subsequently, when the UE receives a random access response on a DL-SCH,the DL-SCH may provide timing alignment information, an RA-preamble ID,an initial uplink grant, and a temporary C-RNTI.

Based on the information, the UE may perform uplink transmission of Msg3of the random access procedure on a UL-SCH. Msg3 may include an RRCconnection request and a UE identifier.

In response, a network may transmit Msg4, which can be considered as acontention resolution message, via a downlink. Upon receiving thismessage, the UE can enter the RRC-connected state.

<Bandwidth Part (BWP)>

In the NR system, a maximum of 400 MHz can be supported per componentcarrier (CC). If a UE operating in such a wideband CC operates with RFfor all CCs turn on all the time, UE battery consumption may increase.Otherwise, considering use cases operating in one wideband CC (e.g.,eMBB, URLLC, mMTC, etc.), different numerologies (e.g., subcarrierspacings (SCSs)) can be supported for different frequency bands in theCC. Otherwise, UEs may have different capabilities for a maximumbandwidth. In consideration of this, an eNB may instruct a UE to operateonly in a part of the entire bandwidth of a wideband CC, and the part ofthe bandwidth is defined as a bandwidth part (BWP) for convenience. ABWP can be composed of resource blocks (RBs) consecutive on thefrequency axis and can correspond to one numerology (e.g., a subcarrierspacing, a cyclic prefix (CP) length, a slot/mini-slot duration, or thelike).

Meanwhile, the eNB can configure a plurality of BWPs for a UE evenwithin one CC. For example, a BWP occupying a relatively small frequencydomain can be set in a PDCCH monitoring slot and a PDSCH indicated by aPDCCH can be scheduled on a BWP wider than the BWP. When UEs converge ona specific BWP, some UEs may be set to other BWPs for load balancing.Otherwise, BWPs on both sides of a bandwidth other than some spectra atthe center of the bandwidth may be configured in the same slot inconsideration of frequency domain inter-cell interference cancellationbetween neighbor cells. That is, the eNB can configure at least oneDL/UL BWP for a UE associated with(=related with) a wideband CC andactivate at least one of DL/UL BWPs configured at a specific time(through L1 signaling or MAC CE or RRC signaling), and switching toother configured DL/UL BWPs may be indicated (through L1 signaling orMAC CE or RRC signaling) or switching to a determined DL/UL BWP mayoccur when a timer value expires on the basis of a timer. Here, anactivated DL/UL BWP is defined as an active DL/UL BWP. However, a UE maynot receive a configuration for a DL/UL BWP when the UE is in an initialaccess procedure or RRC connection is not set up. In such a situation, aDL/UL BWP assumed by the UE is defined as an initial active DL/UL BWP.

<Discontinuous Reception (DRX)>

Discontinuous reception (DRX) refers to an operation mode that enables aUE to reduce battery consumption and to discontinuously receive adownlink channel. That is, the UE configured in DRX may discontinuouslyreceive a DL signal, thereby reducing power consumption.

A DRX operation is performed within a DRX cycle indicating a time periodin which an on duration is periodically repeated. The DRX cycle includesan on duration and a sleep duration (or opportunity for DRX). The onduration indicates a time period in which a UE monitors a PDCCH toreceive the PDCCH.

DRX may be performed in a radio resource control (RRC)_IDLE state (ormode), RRC_INACTIVE state (or mode), or RRC_CONNECTED state (or mode).In the RRC_IDLE state and the RRC_INACTIVE state, DRX may be used todiscontinuously receive a paging signal.

-   -   RRC_IDLE state: State in which a wireless connection (RRC        connection) is not established between a base station and a UE.    -   RRC_INACTIVE state: State in which a wireless connection (RRC        connection) is established between a base station and a UE but        is deactivated.    -   RRC_CONNECTED state: State in which a radio connection (RRC        connection) is established between a base station and a UE.

DRX may be basically divided into idle-mode DRX, connected DRX (C-DRX),and extended DRX.

DRX applied in the idle state may be referred to as idle-mode DRX, andDRX applied in the connected state may be referred to as connected-modeDRX (C-DRX).

Extended/enhanced DRX (eDRX) is a mechanism capable of extending thecycle of idle-mode DRX and C-DRX and may be mainly used for applicationof (massive) IoT. In idle-mode DRX, whether to allow eDRX may beconfigured based on system information (e.g., SIB1). SIB1 may include aneDRX-allowed parameter. The eDRX-allowed parameter is a parameterindicating whether idle-mode extended DRX is allowed.

<Idle-Mode DRX>

In the idle mode, a UE may use DRX to reduce power consumption. Onepaging occasion (PO) is a subframe in which a paging-radio networktemporary identifier (P-RNTI) can be transmitted through a physicaldownlink control channel (PDCCH), a MTC PDCCH (MPDCCH), or a narrowbandPDCCH (NPDCCH) (addressing a paging message for NB-IoT).

In a P-RNTI transmitted through an MPDCCH, PO may indicate a startingsubframe of an MPDCCH repetition. In the case of a P-RNTI transmittedthrough an NPDCCH, when a subframe determined based on a PO is not avalid NB-IoT downlink subframe, the PO may indicate a starting subframeof an NPDCCH repetition. Therefore, a first valid NB-IoT downlinksubframe after the PO is the starting subframe of the NPDCCH repetition.

One paging frame (PF) is one radio frame that may include one or aplurality of paging occasions. When DRX is used, the UE needs to monitoronly one PO per DRX cycle. One paging narrow band (PNB) is one narrowband in which the UE receives a paging message. A PF, a PO and a PNB maybe determined based on DRX parameters provided via system information.

FIG. 19 is a flowchart illustrating an example of performing anidle-mode DRX operation.

Referring to FIG. 19, a UE may receive idle-mode DRX configurationinformation from a base station through higher-layer signaling (e.g.,system information) (S21).

The UE may determine a paging frame (PF) and a paging occasion (PO) tomonitor a PDCCH in a paging DRX cycle based on the idle-mode DRXconfiguration information (S22). In this case, the DRX cycle may includean on duration and a sleep duration (or opportunity for DRX).

The UE may monitor a PDCCH in the PO of the determined PF (S23). Here,for example, the UE monitors only one subframe (PO) per paging DRXcycle. In addition, when the UE receives a PDCCH scrambled with a P-RNTIin the on duration (that is, when paging is detected), the UE maytransition to a connected mode and may transmit and receive data to andfrom the base station.

<Connected-Mode DRX (C-DRX)>

C-DRX refers to DRX applied in the RRC connected state. The DRX cycle ofC-DRX may include a short DRX cycle and/or a long DRX cycle. Here, theshort DRX cycle may be optional.

When C-DRX is configured, a UE may perform PDCCH monitoring for an onduration. When a PDCCH is successfully detected during the PDCCHmonitoring, the UE may operate (or run) an inactivity timer and maymaintain an awake state. However, when the PDCCH is not successfullydetected during the PDCCH monitoring, the UE may enter a sleep stateafter the on duration expires.

When C-DRX is configured, a PDCCH reception occasion (e.g., a slothaving a PDCCH search space) may be discontinuously configured based onthe C-DRX configuration. However, when C-DRX is not configured, a PDCCHreception occasion (e.g., a slot having a PDCCH search space) can becontinuously configured in the present disclosure.

PDCCH monitoring may be limited to a time period set as a measurementgap regardless of a C-DRX configuration.

FIG. 20 illustrates a DRX cycle.

Referring to FIG. 20, the DRX cycle includes an ‘on duration(hereinafter, also referred to as a ‘DRX-on duration’) and an‘opportunity for DRX’. The DRX cycle defines a time interval in whichthe on-duration is cyclically repeated. The on-duration indicates a timeduration in which a UE performs monitoring to receive a PDCCH. If DRX isconfigured, the UE performs PDCCH monitoring during the ‘on-duration’.If there is a PDCCH successfully detected during the PDCCH monitoring,the UE operates an inactivity timer and maintains an awake state. On theother hand, if there is no PDCCH successfully detected during the PDCCHmonitoring, the UE enters a sleep state after the ‘on-duration’ ends.Therefore, when the DRX is configured, in the performing of theprocedure and/or methods described/proposed above, PDCCHmonitoring/reception may be performed discontinuously in a time domain.For example, when the DRX is configured, in the present disclosure, aPDCCH reception occasion (e.g., a slot having a PDCCH search space) maybe configured discontinuously according to the DRX configuration.Otherwise, if the DRX is not configured, in the performing of theprocedure and/or methods described/proposed above, PDCCHmonitoring/reception may be performed continuously in the time domain.For example, when the DRX is not configured, in the present disclosure,a PDCCH reception occasion (e.g., a slot having a PDCCH search space)may be configured continuously. Meanwhile, regardless of whether the DRXis configured, PDCCH monitoring may be restricted in a durationconfigured as a measurement gap.

Table 8 shows a UE procedure related to DRX (RRC_CONNECTED state).Referring to Table 8, DRX configuration information may be receivedthrough higher layer (e.g., RRC) signaling. Whether DRX is ON or OFF maybe controlled by a DRX command of a MAC layer. If the DRX is configured,PDCCH monitoring may be performed discontinuously.

TABLE 8 Type of signals UE procedure 1^(st) step RRC signalling ReceiveDRX configuration (MAC-CellGroupConfig) information 2^(nd) step MAC CEReceive DRX command ((Long) DRX command MAC CE) 3^(rd) step — Monitor aPDCCH during an on-duration of a DRX cycle

MAC-CellGroupConfig may include configuration information required toconfigure a medium access control (MAC) parameter for a cell group.MAC-CellGroupConfig may also include configuration information regardingDRX. For example, MAC-CellGroupConfig may include information fordefining DRX as follows.

-   -   Value of drx-OnDurationTimer: This defines a length of a        starting duration of a DRX cycle. It may be a timer related to a        DRX-on duration.    -   Value of drx-InactivityTimer: This defines a length of a time        duration in which the UE is in an awake state, after a PDCCH        occasion in which a PDCCH indicating initial UL or DL data is        detected.    -   Value of drx-HARQ-RTT-TimerDL: This defines a length of a        maximum time duration until DL retransmission is received, after        DL initial transmission is received.    -   Value of drx-HARQ-RTT-TimerDL: This defines a length of a        maximum time duration until a grant for UL retransmission is        received, after a grant for UL initial transmission is received.    -   drx-LongCycleStartOffset: This defines a time length and a        starting point of a DRX cycle    -   drx-ShortCycle (optional): This defines a time length of a short        DRX cycle.

Herein, if any one of drx-OnDurationTimer, drx-InactivityTimer,drx-HARQ-RTT-TimerDL, and drx-HARQ-RTT-TimerDL is operating, the UEperforms PDCCH monitoring in every PDCCH occasion while maintaining anawake state.

Hereinafter, an integrated access and backhaul (IAB) link is described.For convenience of description, proposed methods are described withreference to a new RAT (NR) system. However, the proposed methods mayalso be applied to other systems including 3GPP LTE/LTE-A systems inaddition to the NR system.

One potential technology intended to enable future cellular networkdeployment scenarios and applications is supporting wireless backhauland relay links, which enables a flexible and highly dense deployment ofNR cells without needing to proportionally densify a transport network.It allows for flexible and very dense deployment.

With massive MIMO or a native deployment of multi-beam system, a greaterbandwidth (e.g., mmWave spectrum) is expected to be available in NR thanin LTE, and thus occasions for the development and deployment ofintegrated access and backhaul links arise. This allows an easydeployment of a dense network of self-backhauled NR cells in anintegrated manner by establishing a plurality of control and datachannels/procedures defined to provide connection or access to UEs. Thissystem is referred to as an integrated access and backhaul (IAB) link.

The following definitions are provided in the disclosure.

-   -   AC(x): Access link between node(x) and UE(s)    -   BH(xy): Backhaul link between node(x) and node(y)

Here, a node may refer to a donor gNB (DgNB) or a relay node (RN), wherea DgNB or a donor node may be a gNB that provides a function ofsupporting a backhaul for IAB nodes.

In the disclosure, for convenience of description, when there are relaynode 1 and relay node 2 and relay node 1 is connected to relay node 2through a backhaul link to relay data transmitted to and received fromrelay node 2, relay node 1 is referred to as a parent node of relay node2 and relay node 2 is referred to as a child node of relay node 1.

The following drawings are provided to explain specific examples of thepresent specification. Terms for specific devices illustrated in thedrawings or terms for specific signals/messages/fields illustrated inthe drawings are provided for illustration, and thus technical featuresof the present specification are not limited by the specific terms usedin the following drawings.

FIG. 21 schematically illustrates an example of a network having anintegrated access and backhaul (IAB) link.

Referring to FIG. 21, relay nodes (rTRPs) may multiplex access andbackhaul links in a time, frequency, or space domain (i.e., a beam-basedoperation).

Different links may operate on the same frequency or on differentfrequencies (which may be referred to as an in-band relay and anout-band relay, respectively). It is important to efficiently supportout-band relays for some NR deployment scenarios, while it is crucial tounderstand requirements for an in-band operation involving closeinterworking with an access link operating on the same frequency toaccommodate duplex constraints and to avoid/mitigate interference.

Furthermore, operating an NR system in a millimeter wave spectrum hasunique challenges, including experiencing severe short-term blockingwhich may not be easily mitigated by a current RRC-based handovermechanism due to a greater scale of time required to complete theprocedure than that for short-term blocking. To overcome short-termblocking in a millimeter wave system, a fast RAN-based mechanism forswitching between rTRPs that does not necessarily require inclusion of acore network may be required. A demand for mitigation of short-termblocking for an NR operation in a millimeter wave spectrum, along with ademand for easier deployment of self-backhauled NR cells, raises a needfor development of an integrated framework that allows fast switching ofaccess and backhaul links. Over-the-air coordination between rTRPs mayalso be considered to mitigate interference and to support end-to-endpath selection and optimization.

The following requirements and aspects need to be achieved by an IAB forNR.

-   -   Efficient and flexible operation for in-band and out-band        relaying in indoor and outdoor scenarios    -   Multi-hop and redundant connection    -   End-to-end path selection and optimization    -   Support of backhaul links with high spectral efficiency    -   Support of legacy NR terminals;

Legacy NR is designed to support half-duplex devices. Thus, half duplexmay be supported and useful in an IAB scenario. Furthermore, IAB deviceswith full duplex may also be considered.

FIG. 22 shows an example of an operation of the IAB system in astandalone (SA) mode and a non-standalone (NSA) mode. Specifically, inFIG. 22, (a) shows an example of an operation of the terminal and IABnode considering NGC in the SA mode, (b) shows an example of anoperation of the IAB node considering NGC in the SA mode and anoperation of the terminal considering EPC in the NSA mode, and (c) showsan example of an operation of the terminal and the IAB node consideringthe EPC in the NSA mode.

The IAB node may operate in SA mode or NSA mode. When operating in NSAmode, the IAB node uses only the NR link for backhauling. A terminalconnected to the IAB node may select an operation mode different fromthat of the IAB node. The terminal may further connect to a differenttype of core network than the connected IAB node. In this case, (e)DECOR ((enhanced) dedicated core network) or slicing may be used for CNselection. An IAB node operating in NSA mode may be connected to thesame or different eNB(s). Terminals operating in the NSA mode may beconnected to the same or different eNB from the IAB node to which theyare connected. FIG. 22 shows an example in consideration of NGC in SAmode and an example in consideration of EPC in NSA mode.

In the IAB scenario, if each relay node (RN) does not have thescheduling capability, the donor gNB (DgNB) must schedule the entirelinks between the DgNB, related relay nodes and terminals. In otherwords, the DgNB should make a scheduling decision for all links bycollecting traffic information from all related relay nodes, and theninform each relay node of the scheduling information.

On the other hand, distributed scheduling can be performed when eachrelay node has a scheduling capability. Then, immediate scheduling ofthe uplink scheduling request of the terminal is possible, and thebackhaul/access link can be used more flexibly by reflecting thesurrounding traffic conditions.

FIG. 23 schematically illustrates an example of the configuration ofaccess and backhaul links.

FIG. 23 shows an example in which a backhaul link and an access link areconfigured when there are a DgNB and IAB relay nodes (RNs). DgNB and RN1are connected via a backhaul link, RN2 is connected to RN1 via abackhaul link, DgNB and UE1 are connected via an access link, RN1 andUE2 are connected via an access link, and RN2 and UE3 are connected viaan access link.

Referring to FIG. 23, the DgNB receives not only a scheduling requestfrom UE1 but also scheduling requests from UE2 and UE3. The DgNBdetermines scheduling of two back links and three access links andreports scheduling results. This centralized scheduling involves ascheduling delay and incurs latency.

On the other hand, distributed scheduling may be performed when eachrelay node has scheduling capability. Accordingly, it is possible toperform immediate scheduling in response to an uplink scheduling requestfrom a UE terminal and to flexibly use backhaul/access links byreflecting surrounding traffic conditions.

FIG. 24 illustrates a link and relationship between IAB nodes.

Referring to FIG. 24, IAB node 1 is connected with IAB node 2 throughbackhaul link A. With respect to backhaul link A, IAB node 1 is a parentnode of IAB node 2, and IAB node 2 is a child node of IAB node 1. IABnode 2 is connected with IAB node 3 via backhaul link B. With respect tobackhaul link B, IAB node 2 is a parent node of IAB node 3, and IAB node3 is a child node of IAB node 2.

Here, each IAB node may perform two functions. One is a mobiletermination (MT), which maintains a wireless backhaul connection to ahigher IAB node or a donor node as, and the other is a distributed unit(DU), which provides an access connection with UEs or a connection withan MT of a lower IAB node.

For example, for IAB node 2, a DU of IAB node 2 functionally establishesbackhaul link B with an MT of IAB node 3, and an MT of IAB node 2functionally establishes backhaul link A with a DU of IAB node 1. Here,a child link of the DU of IAB node 2 may refer to backhaul link Bbetween IAB node 2 and IAB node 3. A parent link of the MT of IAB node 2may refer to backhaul link A between IAB node 2 and IAB node 1.

Hereinafter, initial access of an IAB node is described.

An IAB node may follow the same initial access procedure as used for aUE including cell search, system information acquisition, and randomaccess in order to initially establish a connection to a parent node ora donor node. SSB/CSI-RS-based RRM measurement is the start point of IABnode discovery and measurement.

A method for avoiding a collision in SSB configuration between IAB nodesand an inter-IAB discovery procedure applying the feasibility ofdiscovering an IAB node on the basis of a CSI-RS, half-duplexconstraints, and multi-hop topology need to be taken into consideration.In view of a cell ID used by a given IAB node, the following two casesmay be considered.

Case 1: Donor node and IAB node share the same cell ID.

Case 2: Donor node and IAB node retain separate cell IDs.

Further, a mechanism for multiplexing RACH transmissions from UEs andRACH transmissions from IAB nodes also needs to be considered.

In the case of standalone (SA) deployment, the initial IAB nodediscovery (stage 1) by the MT follows the same initial access procedurewith the terminal including a cell based on the same SSB that may beused by access terminals, system information acquisition, and randomaccess to initially establish a connection with a parent IAB node or anIAB donor.

In the case of non-standalone (NSA) deployment (from theconnection/access terminal point of view), the IAB node MT follows theaforementioned stage 1 initial access in SA deployment (from the accessterminal point of view) when performing the initial access on the NRcarrier. An SSB/RMSI period assumed by the MTs for initial access may belonger than 20 ms assumed for rel-15 terminals of NR, and one of thecandidate values 20 ms, 40 ms, 80 ms, and 160 ms is selected.

Here, this means that the candidate parent IAB nodes/donors shouldsupport both the NSA functionality for the UE and the SA functionalityfor the MT on the NR carrier.

When the IAB node MT performs the initial connection on the LTE carrier,stage 2 solutions may be used with parent selection of the IAB node bythe MT on the NR carrier.

Hereinafter, backhaul link measurement is described.

It is necessary to consider measuring a plurality of backhaul links forlink management and path selection. To support half-duplex constraintsfrom the perspective of a given IAB node, IAB supports detecting andmeasuring candidate backhaul links (after initial access) usingresources orthogonal to resources used an access UEs for cell detectionand measurement. Here, the following aspects may be further considered.

-   -   TDM of a plurality of SSBs (e.g., according to hop order, cell        ID, or the like)    -   SSB muting across IAB nodes    -   Multiplexing of SSBs for access UEs and IAB nodes in a half        frame or across half frames    -   IAB node discovery signal (e.g., CSI-RS) that is TDMed with SSB        transmission    -   Use of off-raster SSB    -   Transmission period for backhaul link detection and measurement,        which is different from a period used by access UEs.

It is necessary to further consider a coordination mechanism fordifferent solutions including a coordination mechanism for measurementtime and reference signal (RS) transmission for IAB nodes.

It may be considered to enhance an SMTC and a CSI-RS configuration inorder to support RRM measurement for IAB nodes.

For the purpose of backhaul link RSRP/RSRQ RRM measurement, IAB supportsSSB-based and CSI-RS-based solutions.

After the IAB node DU is activated, for the purpose of inter IAB nodeand donor detection (stage 2), the IAB inter-node discovery procedureneeds to consider a half-duplex limitation for the IAB node andmulti-hop topology. The following solution is supported: SSB-basedsolution—use of SSBs orthogonal (TDM and/or FDM) to SSBs used for accessterminals.

Hereinafter, backhaul link management is described.

The IAB node supports a mechanism for detecting/recovering backhaul linkfailure.

Enhancements to beam failure recovery (BFR) and radio link failure (RLF)procedures are advantageous and should be supported for NR IAB asfollows.

-   -   Improvement of support for interaction between beam failure        recovery success indication and RLF.    -   Improvement of current beam management procedures for faster        beam switching/coordination/recovery to avoid backhaul link        outage should be considered for IAB nodes.

Further, for example, when the backhaul link of the parent IAB nodefails, etc., the need for an additional backhaul link conditionnotification mechanism from the parent IAB node to the child IAB nodeand the need for the corresponding IAB node operation is discussed.Solutions to avoid RLF in child IAB node due to parent backhaul linkfailure should be supported.

Hereinafter, a mechanism for path switching or transmission/reception ina plurality of backhaul links is described.

It is necessary to consider a mechanism for simultaneous and efficientpath switching or transmission/reception in a plurality of backhaullinks (e.g., a multi-Tx/Rx (TRP) operation and intra-frequency dualconnectivity).

Hereinafter, scheduling of backhaul and access links is described.

Downlink transmission of an IAB node (i.e., transmission from the IABnode to a child IAB node served by the IAB node via a backhaul link andtransmission from the IAB node to UEs served by the IAB node via anaccess link) may be scheduled by the IAB node itself. Uplinktransmission of the IAB node (i.e., transmission from the IAB node to aparent IAB node thereof or a donor node via a backhaul link) may bescheduled by the parent IAB node or the donor node.

Hereinafter, multiplexing of backhaul and access links is described.

In IAB, an IAB node supports time-division multiplexing (TDM),frequency-division multiplexing (FDM), and spatial-division multiplexing(SDM) between access and backhaul links according to half-duplexconstraints. It is necessary to consider an efficient TDM/FDM/SDMmechanism for access/backhaul traffic over a multi-hop considering thehalf-duplex constraints of the IAB node. For various multiplexingoptions, the following aspects may be further considered.

-   -   Mechanism for orthogonally partitioning time slots or frequency        resources between access and backhaul links over one or a        plurality of hops    -   Use of different DL/UL slot configurations for access and        backhaul links    -   DL and UL power control enhancement and timing requirements to        allow intra-panel FDM and SDM in backhaul and access links    -   Interference management including cross-link interference.

Hereinafter, resource coordination is described.

It is necessary to consider a mechanism for scheduling coordination,resource allocation, and path selection across an IAB node/donor nodeand a plurality of backhaul hops. It is necessary to support semi-staticcoordination of resources (frequency, time in terms of slot/slot format,or the like) for IAB nodes (in timescale of RRC signaling). Thefollowing aspects may be further considered.

-   -   Distributed or centralized coordination mechanism    -   Resource granularity (e.g., TDD configuration pattern) of a        necessary signal    -   Exchange of layer-1 (L1) and/or layer-3 (L3) measurements        between IAB nodes    -   Exchange of information about topology affecting the design of a        physical layer of a backhaul link (e.g., hop order)    -   Coordination of resources (frequency, time in terms of slot/slot        format, or the like) faster than semi-static coordination

Hereinafter, IAB node synchronization and timing alignment aredescribed.

Feasibility of over-the-air (OTA) synchronization and the impact oftiming misalignment on IAB performance (e.g., the number of supportablehops) should be considered. Assuming a timing requirement of 3 us orless in IAB nodes within overlapping coverage, TA-based OTAsynchronization can support multi-hop IAB networks (up to 5 hops) forFR2. TA-based OTA synchronization may not be sufficient to supportmultiple hops in FR1.

The following levels of alignments need to be considered between an IABnode/donor node or within an IAB node:

-   -   Slot-level alignment    -   Symbol-level alignment    -   No alignment.

A mechanism for timing alignment in a multi-hop IAB network isdiscussed. IAB supports TA-based synchronization between IAB nodesincluding multiple backhaul hops. Improvements to existing timingalignment mechanisms including TAs required for IAB nodes to supportdifferent transmission timing alignment cases are discussed.

The following transmission timing alignment case across IAB nodes andIAB donors is discussed.

-   -   Case 1: DL transmission timing alignment across IAB node and IAB        donor: If downlink transmission and uplink reception are not        well aligned at the parent node, the child node requires        additional information on the alignment to properly set the        downlink transmission timing of its own for the OTA-based timing        and synchronization.    -   Case 2: Downlink and uplink transmission timings are aligned for        one IAB node.    -   Case 3: Downlink and uplink reception timings are aligned for        one IAB node.    -   Case 4: For one IAB node, in the case of transmission using Case        2 when receiving using Case 3.    -   Case 5: Case 4 for backhaul link timing and Case 1 for access        link timing for one IAB node in different time slots    -   Case 6: Sum of the downlink transmission timing of Case 1 and        the uplink transmission timing of Case 2: The downlink        transmission timing of all IAB nodes is aligned with a downlink        timing of the parent IAB node or the donor; The uplink        transmission timing of the IAB node may be aligned with the        downlink transmission timing of the IAB node.    -   Case 7: Sum of the downlink transmission timing of Case 1 and        the uplink reception timing of Case 3: The downlink transmission        timings of all IAB nodes are aligned with the downlink timings        of the parent IAB node or the donor; The uplink reception timing        of the IAB node may be aligned with the downlink reception        timing of the IAB node; If the downlink transmission and the        uplink reception are not well aligned in the parent node, the        child node needs additional information on the alignment in        order to properly set its downlink transmission timing for        OTA-based timing and synchronization.

Impact of different cases on TDM/FDM/SDM multiplexing of parent andchild links, potential impact of incomplete timing adjustment, overheadof required downlink/uplink switching gap, cross-link interference,feasibility when one IAB node is connected to one or a plurality ofparent nodes, and the impact of access terminals (in particular,compatibility with rel-15 terminals) are discussed.

Case 1 is supported for both access and backhaul link transmissiontiming alignment.

Cases 2-5 are not supported for IAB.

The use of case 6 for IAB nodes, if supported, should be under thecontrol of the parent or network. To enable alignment of downlinktransmission between IAB nodes, examples of the following solutions havebeen identified.

-   -   Alternative 1: IAB nodes may have to perform parallel (always        time multiplexed) Case 1 and Case 6 uplink transmissions.    -   Alternative 2: Signaling between the parent and the IAB node on        a time difference between downlink transmission and uplink        reception timing at the parent node to correct potential        misalignment of the downlink transmission timing at the child        node: The child IAB node itself compare a corresponding        difference between the downlink transmission timing and the        backhaul reception timing of its own; If the signaled difference        of the parent node is greater than that measured by the child        node and if the transmission timing is smaller, the child node        advances its transmission timing.

Here, Alternative 1 and Alternative 2 may have to maintain separatereception timing in the parent node for Case 6 uplink transmission fromother child nodes.

Case 7 is compatible for the rel-15 terminals by introducing TDM betweenthe child IAB node/rel-16 terminals supporting an effective negative TAand the new TA value and the child IAB node/terminal that does notsupport the new TA value. To enable alignment between downlink anduplink reception within the IAB node, examples of the followingsolutions have been identified.

-   -   Alternative 1: Negative initial time alignment (TA) to be        applied to the child node of the IAB node to which the case 7        timing is applied is introduced    -   Alternative 2: In the IAB node, a positive TA that enables        symbol alignment rather than slot alignment between downlink        reception and uplink reception is applied.    -   Alternative 3: Signaling of a relative offset of the most recent        TA value, to be applied to the child node of the IAB node to        which the case 7 timing is applied to achieve an efficient        negative TA.    -   In addition to OTA synchronization, other techniques such as        GNSS and PTP may be used to obtain synchronization between IAB        nodes.

Hereinafter, cross-link interference measurement and management will bedescribed.

The impact of cross-link interference (CLI) on access and backhaul links(including spanning multiple hops) must be considered. Furthermore,interference measurement and management solutions should be considered.

Hereinafter, a CLI mitigation technique is described.

A CLI mitigation technique including advanced receiver and transmittercoordination needs to be considered, and priorities need to bedetermined in terms of complexity and performance. The CLI mitigationtechnique needs to be able to manage the following inter-IABinterference scenarios.

-   -   Case 1: A victim IAB node performs DL reception via an MT        thereof, and an interfering IAB node performs UL transmission        via an MT thereof    -   Case 2: A victim IAB node performs DL reception via an MT        thereof, and an interfering IAB node performs DL transmission        via a DU thereof    -   Case 3: A victim IAB node performs UL reception via a DU        thereof, and an interfering IAB node performs UL transmission        via an MT thereof    -   Case 4: A victim IAB node performs UL reception via a DU        thereof, and an interfering IAB node performs DL transmission        via a DU thereof.

When a given IAB node performs FDM/SDM reception between access andbackhaul links, interference experienced by the IAB node needs to befurther taken into consideration.

Hereinafter, spectral efficiency enhancement is described.

It is necessary to consider supporting 1024 quadrature amplitudemodulation (QAM) for a backhaul link.

FIG. 25 is a diagram illustrating an example of a downlinktransmission/reception operation.

Referring to FIG. 25, the base station schedules downlink transmissionsuch as frequency/time resources, transport layer, downlink precoder,MCS, and the like (S2501). In particular, the base station may determinea beam for PDSCH transmission to the terminal through the beammanagement operations described above. Then, the terminal receivesdownlink control information (DCI) for downlink scheduling (that is,including scheduling information of the PDSCH) on the PDCCH from thebase station (S2502). DCI format 1_0 or 1_1 may be used for downlinkscheduling, and in particular, DCI format 1_1 includes the followinginformation: Identifier for DCI formats, Bandwidth part indicator,Frequency domain resource assignment, Time domain resource assignment,PRB bundling size indicator, Rate matching indicator, ZP CSI-RS trigger,Antenna port(s), transmission configuration indication (TCI), SRSrequest, DMRS (Demodulation Reference Signal) sequence initialization.

In particular, according to each state indicated in the antenna port(s)field, the number of DMRS ports may be scheduled, and single-user(SU)/multi-user (MU) transmission scheduling is possible. In addition,the TCI field consists of 3 bits, and the QCL for the DMRS isdynamically indicated by indicating a maximum of 8 TCI states accordingto the TCI field value. Then, the terminal receives downlink data fromthe base station on the PDSCH (S2503). When the UE detects a PDCCHincluding DCI format 1_0 or 1_1, it decodes the PDSCH according to anindication by the corresponding DCI.

Here, when the terminal receives a PDSCH scheduled by DCI format 1, theterminal may be configured for a DMRS configuration type by a higherlayer parameter ‘dmrs-Type’, and the DMRS type is used to receive thePDSCH. In addition, the terminal may be configured for the maximumnumber of front-loaded DMRS symbols for the PDSCH by the upper layerparameter ‘maxLength’.

For DMRS configuration type 1, when a single codeword is scheduled forthe terminal and an antenna port mapped with an index of {2, 9, 10, 11or 30} is specified, or if the terminal is scheduled with two codewords,the terminal assumes that all remaining orthogonal antenna ports are notassociated with PDSCH transmission to another terminal. Or, in the caseof DMRS configuration type 2, when a single codeword is scheduled forthe terminal and an antenna port mapped with an index of {2, 10 or 23}is specified, or if the terminal is scheduled with two codewords, theterminal assumes that all remaining orthogonal antenna ports are notassociated with PDSCH transmission to another terminal.

When the terminal receives the PDSCH, it may be assumed that theprecoding granularity P′ is consecutive resource blocks in the frequencydomain. Here, P′ may correspond to one of {2, 4, broadband}. If P′ isdetermined to be a broadband (wideband), the terminal does not expect tobe scheduled with non-contiguous PRBs, and the terminal may assume thatthe same precoding is applied to the allocated resource. On the otherhand, when P′ is determined to be any one of {2, 4}, a precodingresource block group (PRG) is divided into P′ consecutive PRBs. Theactual number of consecutive PRBs in each PRG may be one or more. Theterminal may assume that the same precoding is applied to consecutivedownlink PRBs in the PRG.

In order for the terminal to determine a modulation order, a target coderate, and a transport block size in the PDSCH, the terminal first readsthe 5-bit MCD field in the DCI, and determines the modulation order andthe target code rate. Then, the terminal reads the redundancy versionfield in the DCI and the redundancy version is determined. Then, theterminal determines a transport block size by using the number of layersbefore rate matching and the total number of allocated PRBs.

FIG. 26 is a diagram illustrating an example of an uplinktransmission/reception operation.

Referring to FIG. 26, the base station schedules uplink transmissionsuch as frequency/time resources, a transport layer, an uplink precoder,an MCS, and the like (S2601). In particular, the base station candetermine the beam for the terminal for PUSCH transmission through thebeam management operations described above. Then, the terminal receivesthe DCI for uplink scheduling (that is, including the schedulinginformation of the PUSCH) on the PDCCH from the base station (S2602).DCI format 0_0 or 0_1 may be used for uplink scheduling. In particular,DCI format 0_1 includes the following information: Identifier for DCIformats, UL/SUL indicator, Bandwidth part indicator, Frequency domainresource assignment, Time domain resource assignment, Frequency hoppingflag, MCS: Modulation and coding scheme, SRI: SRS resource indicator,Precoding information and number of layers, Antenna port(s), SRSrequest, DMRS sequence initialization, UL-SCH indicator.

In particular, SRS resources configured in the SRS resource setassociated with the higher layer parameter ‘usage’ may be indicated bythe SRS resource indicator field. In addition, ‘spatialRelationInfo’ maybe configured for each SRS resource, and the value may be one of {CRI,SSB, SRI}.

Then, the terminal transmits uplink data to the base station on thePUSCH (S2603). When the terminal detects a PDCCH including DCI format0_0 or 0_1, the terminal transmits a corresponding PUSCH according to anindication by the corresponding DCI. For PUSCH transmission, twotransmission schemes are supported: codebook-based transmission andnon-codebook-based transmission.

In the case of codebook-based transmission, when the upper layerparameter ‘txConfig’ is set to ‘codebook’, the terminal is set tocodebook-based transmission. On the other hand, when the upper layerparameter ‘txConfig’ is set to ‘nonCodebook’, the terminal is set tonon-codebook-based transmission. If the upper layer parameter ‘txConfig’is not set, the terminal does not expect to be scheduled by DCI format0_1. When PUSCH is scheduled by DCI format 0_0, PUSCH transmission isbased on a single antenna port. In the case of codebook-basedtransmission, the PUSCH may be scheduled in DCI format 0_0, DCI format0_1, or semi-statically. If this PUSCH is scheduled by DCI format 0_1,as given by the SRS resource indicator field and the precodinginformation and number of layers field, a PUSCH transmission precoder isdetermined based on a SRI, a transmit precoding matrix indicator (TPMI),and a transmission rank from DCI. The TPMI is used to indicate aprecoder to be applied across an antenna port, and corresponds to theSRS resource selected by the SRI when multiple SRS resource areconfigured. Alternatively, when a single SRS resource is configured, theTPMI is used to indicate a precoder to be applied across an antennaport, and corresponds to the single SRS resource. A transmissionprecoder is selected from the uplink codebook having the same number ofantenna ports as the upper layer parameter ‘nrofSRS-Ports’. When theupper layer in which the terminal is set to ‘codebook’ is set to theparameter ‘txConfig’, at least one SRS resource is configured in theterminal. The SRI indicated in slot n is associated with the most recenttransmission of the SRS resource identified by the SRI, where the SRSresource precedes the PDCCH carrying the SRI (i.e., slot n).

In the case of non-codebook-based transmission, the PUSCH may bescheduled in DCI format 0_0, DCI format 0_1, or semi-statically. Whenmultiple SRS resources are configured, the UE may determine a PUSCHprecoder and a transmission rank based on wideband SRI, where the SRI isgiven by an SRS resource indicator in DCI or a higher layer parameter‘srs-Resourcelndicator’. The UE uses one or multiple SRS resources forSRS transmission, where the number of SRS resources may be configuredfor simultaneous transmission within the same RB based on UEcapabilities. Only one SRS port is configured for each SRS resource.Only one SRS resource may be set as the upper layer parameter ‘usage’set to ‘nonCodebook’. The maximum number of SRS resources that can beconfigured for non-codebook-based uplink transmission is 4. The SRIindicated in slot n is associated with the most recent transmission ofthe SRS resource identified by the SRI, where the SRS transmissionprecedes the PDCCH carrying the SRI (i.e., slot n).

Hereinafter, an uplink grant will be described.

In NR, an uplink grant can be divided into (1) a dynamic grant, or withgrant and (2) a configured grant, or grant free or without grant.

FIG. 27 shows an example of an uplink grant. FIG. 27 (a) shows anexample of a dynamic grant, and FIG. 27 (b) shows an example of aconfigured grant.

A dynamic grant refers to a scheduling-based data transmission/receptionmethod of a base station in order to maximize resource utilization. Thismeans that, when there is data to be transmitted, the terminal maypreferentially request uplink resource allocation to the base stationand transmit data using only uplink resources allocated from the basestation. For efficient use of uplink radio resources, the base stationneeds to know what type of data to transmit and how much data totransmit in the uplink for each terminal. Accordingly, the terminaldirectly transmits information about uplink data it wants to transmit tothe base station, and the base station can allocate uplink resources tothe corresponding terminal based on the information. In this case, theinformation on the uplink data transmitted from the terminal to the basestation is the amount of uplink data stored in its buffer, and isreferred to as a buffer status report (BSR). The BSR is transmittedusing a MAC control element when a resource on the PUSCH in the currentTTI is allocated to the UE and a reporting event is triggered.

Referring to FIG. 27 (a), an uplink resource allocation procedure foractual data is exemplified when the terminal does not allocate uplinkradio resources for buffer status report (BSR) to the terminal. That is,in the case of a terminal switching the state of the active mode fromthe DRX mode, since there is no pre-allocated data resource, it isnecessary to request a resource for uplink data starting with SRtransmission through the PUCCH, and in this case, the uplink resourceallocation procedure of 5 steps is used.

Referring to FIG. 27 (a), when the PUSCH resource for transmitting theBSR is not allocated to the UE, the UE first transmits a schedulingrequest (SR) to the base station in order to allocate the PUSCHresource. When a reporting event has occurred, but a radio resource isnot scheduled to the UE on the PUSCH in the current TTI, the schedulingrequest is used for the UE to request the base station to allocate PUSCHresources for uplink transmission. That is, the UE transmits the SR onthe PUCCH when the regular BSR is triggered but the UE does not haveuplink radio resources for transmitting the BSR to the base station. TheUE transmits the SR through the PUCCH or initiates a random accessprocedure depending on whether the PUCCH resource for the SR isconfigured. Specifically, the PUCCH resource through which the SR can betransmitted is UE-specifically configured by a higher layer (e.g., RRClayer), and the SR configuration includes an SR periodicity and an SRsubframe offset information. Upon receiving an uplink grant for a PUSCHresource for BSR transmission from the base station, the terminaltransmits the triggered BSR through the PUSCH resource allocated by theuplink grant to the base station. The base station checks the amount ofdata that the terminal actually transmits in uplink through the BSR, andtransmits an uplink grant for PUSCH resources for actual datatransmission to the terminal. The UE receiving an uplink grant foractual data transmission transmits actual uplink data to the basestation through the allocated PUSCH resource.

The configured grant method will be described by referring FIG. 27 (b).

The terminal receives a resource configuration for transmission ofuplink data without a grant from the base station. The resourceconfiguration may be performed only with RRC signaling (type 1), or maybe performed with L1 (layer-1) signaling and RRC signaling (type 2).Then, the terminal performs initial transmission to the base stationbased on the resource configuration received without the grant. In thiscase, the initial transmission may be repeated, and repetition of theinitial transmission for the same transport block may be performed Ktimes (K≥1).

Resources for initial transmission by a configured grant may or may notbe shared between one or more terminals.

When the initial transmission by the configured grant fails, the basestation may transmit a grant for retransmission of a TB related to theinitial transmission to the terminal. At this time, the base stationneeds to identify the terminal even if a collision occurs. A terminalperforming uplink transmission without an uplink grant may be identifiedbased on time/frequency resources and reference signal (RS) parameters.

The base station may allocate different DMRS resources to differentterminals sharing the same PUSCH resource. And, when the terminalperforms retransmission, the transmission is switched to a grant-basedtransmission, the UE receives a grant from the base station, and the UEperforms retransmission based on the grant. That is, the terminalperforms initial transmission without a grant, but performsretransmission based on a grant.

FIG. 28 is a diagram illustrating an example of a grant-free initialtransmission.

Hereinafter, PUCCH will be described.

FIG. 29 shows an example of a conceptual diagram of uplink physicalchannel processing.

Each of the blocks shown in FIG. 29 may be performed in each module inthe physical layer block of the transmission device. More specifically,the uplink signal processing in FIG. 29 may be performed by theprocessor of the terminal/base station described in this specification.Referring to FIG. 28, uplink physical channel processing may beperformed through the processes of scrambling, modulation mapping, layermapping, transform precoding, precoding, resource element mapping,SC-FDMA signal generation. Each of the above processes may be performedseparately or together in each module of the transmission device.

More specifically, for each of the above processes, for one codeword,the transmission device may scramble coded bits in the codeword by ascrambling module and then transmit it through a physical channel. Thescrambled bits are modulated into complex modulation symbols by amodulation mapping module. The modulation mapping module may modulatethe scrambled bit according to the predetermined modulation scheme andarrange it as a complex modulation symbol representing a position on asignal constellation. There is no restriction on the modulation scheme,and pi/2-BPSK, m-PSK, or m-QAM or the like may be used for modulation ofthe encoded data. The complex modulation symbol may be mapped to one ormore transport layers by a layer mapping module. The complex modulationsymbols on each layer may be precoded by a precoding module fortransmission on the antenna port. Here, the precoding module may performafter performing transform precoding on the complex modulation symbol asshown in FIG. 29. The precoding module processes the complex modulationsymbol in a MIMO method according to multiple transmit antennas tooutput antenna-specific symbols, and may distribute the antenna-specificsymbols to a corresponding resource element mapping module. The output zof the precoding module can be obtained by multiplying the output y ofthe layer mapping module by the precoding matrix W of N by M. Here, N sthe number of antenna ports, and M is the number of layers. The resourceelement mapping module maps to the appropriate resource element in thevirtual resource block allocated for transmitting the complexdemodulation symbol for each antenna port. The resource element mappingmodule may allocate complex modulation symbols to appropriatesubcarriers and multiplex them according to users. The SC-FDMA signalgeneration module may generate a complex-valued time domain OFDM symbolsignal by modulating a complex modulation symbol using a specificmodulation method, for example, an OFDM method. The signal generationmodule may perform IFFT on an antenna-specific symbol, and a cyclicprefix (CP) may be inserted into a time domain symbol on which the IFFTis performed. The OFDM symbol undergoes digital-to-analog conversion,frequency upconversion, and the like, and is transmitted to a receiverthrough each transmit antenna. The signal generation module may includean IFFT module and a CP inserter, a DAC converter, a frequency uplinkconverter, and the like.

The signal processing process of the receiving device may be configuredas a reverse of the signal processing process of the transmittingdevice. For details, refer to the above and FIG. 29.

Next, PUCCH will be described.

PUCCH supports a number of formats, and the PUCCH formats may beclassified by a symbol duration, a payload size, and multiplexing. Table9 below is a table showing an example of the PUCCH format.

TABLE 9 PUCCH length in Number Format OFDM symbols of bits Usage Etc. 01-2 ≤2 1 sequence selection 1  4-14 ≤2 2 sequence modulation 2 1-2 >2 4CP-OFDM 3  4-14 >2 8 DFT-s-OFDM (no UE multiplexing) 4  4-14 >2 16DFT-s-OFDM (Pre DFT OCC)

The PUCCH formats of Table 9 can be largely divided into (1) short PUCCHand (2) long PUCCH. PUCCH format 0 and 2 may be included in a shortPUCCH, and PUCCH formats 1, 3, and 4 may be included in a long PUCCH.

FIG. 30 shows an example of an NR slot in which a PUCCH is transmitted.

The UE transmits one or two PUCCHs through a serving cell in differentsymbols within one slot. When two PUCCHs are transmitted in one slot, atleast one of the two PUCCHs has a short PUCCH structure. That is, in oneslot, (1) transmission of short PUCH and short PUCCH is possible, (2)transmission of long PUCCH and short PUCCH is possible, but (3)transmission of long PUCCH and long PUCCH is impossible.

A HARQ-ACK operation will be described in relation to a terminaloperation for reporting control information. HARQ in NR has thefollowing characteristics.

1. HARQ-ACK feedback of 1 bit per TB (transport block) is supported.Here, the operation of one DL HARQ process is supported for someterminals, whereas the operation of one or more DL HARQ processes issupported for a given terminal.

2. The terminal supports a set of minimum HARQ processing time. Here,the minimum HARQ processing time means the minimum time required for theterminal from receiving downlink data from the base station to thecorresponding HARQ-ACK transmission timing. In this regard, two types ofterminal processing times N1 and K1 may be defined according to (1)symbol granularity and (2) slot granularity. First, from the UE point ofview, N1 represents the number of OFDM symbols required for UEprocessing from the end of PDSCH reception to the earliest possiblestart of the corresponding HARQ-ACK transmission. The N1 may be definedas shown in Tables 10 and 11 below according to OFDM numerology (i.e.,subcarrier spacing (SCS)) and a DMRS pattern.

TABLE 10 HARQ 15 30 60 120 Timing KHz KHz KHz KHz configurationParameter Units SCS SCS SCS SCS Front-loaded N1 Symbols 8 10 17 20 DMRSonly Front-loaded N1 Symbols 13 13 20 24 DMRS only + additional DMRS

TABLE 11 HARQ Timing 15 KHz 30 KHz 60 KHz configuration Parameter UnitsSCS SCS SCS Front-loaded N1 Symbols 3 4.5 9(FR1) DMRS only Front-loadedN1 Symbols [13] [13] [20] DMRS only + additional DMRS

And, K1 represents the number of slots from the slot of the PDSCH to theslot of the corresponding HARQ-ACK transmission.

FIG. 31 is a diagram illustrating an example of the HARQ-ACK timing(K1).

In FIG. 31, K0 represents the number of slots from a slot having adownlink grant PDCCH to a slot having a corresponding PDSCHtransmission, and K2 represents the number of slots from a slot havingan uplink grant PDCCH to a slot having a corresponding PUSCHtransmission. That is, K0, K1, and K2 can be briefly summarized as shownin Table 12 below.

TABLE 12 A B K0 DL scheduling DCI Corresponding DL data transmission K1DL data reception Corresponding HARQ-ACK K2 UL scheduling DCICorresponding UL data transmission

The slot timing between A and B is indicated by a field in DCI from theset of values. In addition, NR supports different minimum HARQprocessing times between terminals.

The HARQ processing time includes a delay between a downlink datareception timing and a corresponding HARQ-ACK transmission timing and adelay between an uplink grant reception timing and the correspondinguplink data transmission timing. The terminal transmits the capabilityof its minimum HARQ processing time to the base station. Asynchronousand adaptive downlink HARQ are supported at least in enhanced mobilebroadband (eMBB) and ultra-reliable low latency communication (URLLC).More specific details about eMBB and URLLC will be described later.

From a UE perspective, HARQ ACK/NACK feedback for a plurality ofdownlink transmissions in the time domain may be transmitted in oneuplink data/control domain. The timing between downlink data receptionand a corresponding acknowledgment is indicated by a field in DCI from aset of values, the set of values being set by a higher layer. The timingis defined at least for a case where the timing is not known to the UE.

3. Codebook block group (CBG)-based transmission with single/multi-bitHARQ-ACK feedback is supported, and specifically has the followingcharacteristics.

(1) CBG-based (re)transmission is allowed only for the same TB of theHARQ process.

(2) A CBG may include all CBs of a TB regardless of the size of the TB.In this case, the UE reports a single HARQ ACK bit for the TB.

(3) A CBG may contain one CB.

(4) CBG granularity may be configured by a higher layer.

If the UE receives the PDSCH without receiving the corresponding PDCCH,or the UE receives the PDCCH indicating the release of the SPS PDSCH,the UE generates one corresponding HARQ-ACK information bit. When the UEis not provided with the higher layer parameterPDSCH-CodeBlockGroupTransmission, the UE generates one HARQ-ACKinformation bit per transport block. The UE does not expect to beinstructed to transmit HARQ-ACK information for more than two SPS PDSCHreceptions on the same PUCCH.

When the UE receives the upper layer parameterPDSCH-CodeBlockGroupTransmission for the serving cell, The UE receives aPDSCH including code block groups (CBGs) of transport blocks, The UE isprovided with a higher layer parametermaxCodeBlockGroupsPerTransportBlock indicating the maximum number ofCBGs (NCBG/TB, maxHARQACK) for generating each HARQ-ACK information bitsfor receiving a transport block for a serving cell. In addition, thedetermination of the HARQ-ACK codebook may be divided into determinationof a type-1 HARQ-ACK codebook and determination of a type-2 HARQ-ACKcodebook. Parameters related to CBG group-based HARQ-ACK transmissionmay be as follows, and corresponding parameters may be configuredthrough higher layer signaling (e.g., RRC, DCI).

-   -   codeBlockGroupTransmission: a parameter indicating whether it is        CBG-based transmission    -   maxCodeBlockGroupsPerTransportBlock: A parameter indicating the        maximum number of CBGs per TB. The value of the parameter may        have 2, 4, 6, or 8.    -   harq-ACK-Codebook: a parameter indicating whether the HARQ-ACK        codebook is semi-static or dynamic.    -   C: a parameter indicating the number of CBs in the TB    -   harq-ACK-Spatial-Bundling: a parameter indicating whether        spatial bundling of HARQ ACKs is enabled    -   CBG transmission information (CBGTI): a parameter indicating        information through which CBG is transmitted, included in DCI        format 1_1.    -   CBG flushing out information (CBGFI): a parameter indicating        whether CBG is processed differently for soft-buffer/HARQ        combining, included in DCI format 1_1.

In addition to this, a parameter indicating the number of CBGs in the TBmay be included or defined in higher layer signaling (e.g., RRC, DCI).

As described above, the IAB node may have an aspect that operates like aterminal in relation to a base station (or a parent node). In addition,the IAB node may have an aspect that operates like a base station inrelation to a terminal (or child node) connected to it. In considerationof this point, in the present specification, the UE/terminal may be anIAB node. For example, in the description/drawing related to thedownlink transmission/reception operation between the base station andthe terminal, the terminal may be an IAB node. Alternatively, the basestation may be an IAB node. Similarly, in the description/drawingrelated to the uplink transmission/reception operation, the terminal/UEmay be an IAB node, or the base station may be an IAB node.

Hereinafter, proposals of the present disclosure will be described inmore detail.

The following drawings are provided to describe specific examples of thepresent disclosure. Since the specific designations of devices or thedesignations of specific signals/messages/fields illustrated in thedrawings are provided for illustration, technical features of thepresent disclosure are not limited to specific designations used in thefollowing drawings.

The disclosure is described assuming an in-band environment but may alsobe applied in an out-band environment. Further, the disclosure isdescribed in consideration of an environment in which a donor-gNB(DgNB), a relay node (RN), and/or a UE perform a half-duplex operationbut may also be applied in an environment a DgNB, an RN, and/or a UEperform a full-duplex operation.

The present disclosure proposes a method for time domain synchronizationof IAB nodes in an IAB system configured with multiple hops, inparticular, methods for aligning downlink transmission timing. In otherwords, the downlink transmission timing may be the same between IABnodes.

From an MT perspective of an IAB node, the following time-domainresources may be indicated for a parent link.

-   -   downlink (DL) time resource    -   uplink (UL) time resource    -   flexible (F) time resource

In an IAB node DU aspect, a child link may have the following timeresource types.

-   -   downlink (DL) time resource    -   uplink (UL) time resource    -   flexible (F) time resource    -   not-available (NA) time resource (resource not used for a        communication in a DU child link)

Meanwhile, each of a DL time resource, a UL time resource, and aflexible time resource of a DU child link may belong to one of thefollowing two categories.

-   -   hard resource: a time resource always available for a DU child        link    -   soft resource: a time resource for which an availability of a        time resource for a DU child link is controlled by a parent node        explicitly or implicitly

In an IAB node DU aspect, for a child link, four types of time resourcesincluding a DL, a UL, an F, and an NA are present. The NA time resourcemeans a resource which is not used for a communication on a DU childlink.

Each of the DL, UL, and F time resources in a DU child link may be ahard resource or a soft resource. The hard resource may mean a resourcealways available for a communication on a DU child link. However, thesoft resource may be a resource of which availability for acommunication on a DU child link is controlled explicitly and/orimplicitly by a parent node.

In the present disclosure, a configuration for a link direction and alink availability of a time resource for a DU child link may be called aDU configuration. The DU configuration may be used for effectivemultiplexing and interference handling between IAB nodes. For example,the DU configuration may be used to indicate whether a certain link is avalid link for a time resource between a parent link and a child link.In addition, only a subset of child nodes are configured to use a timeresource for a DU operation, and the DU configuration may be used forinterference handling. Considering such an aspect, the DU configurationmay be more efficient when the DU configuration is configuredsemi-statically.

Meanwhile, similar to a slot format indication (SFI) configuration foran access link, an IAB node MT may have three types of time resourcesincluding a DL, a UL, and an F for its own parent link.

FIG. 32 illustrates an MT configuration and a DU configuration.

Referring to FIG. 32, there are IAB node A, IAB node B, and IAB node C,a parent node of IAB node B is IAB node A, and a child node of IAB nodeB is IAB node C.

Referring to FIG. 32, an IAB node may receive an MT configurationindicating link direction information about a parent link between aparent node thereof and the IAB node for communication with the parentnode. In addition, the IAB node may receive a DU configurationindicating link direction and availability information that can be usedfor communication with a child node thereof.

For example, an MT configuration of IAB node B may include linkdirection information about a link between IAB node A and IAB node Bfrom the perspective of IAB node B, and a DU configuration of IAB node Bmay include link direction and availability information about a linkbetween IAB node B and IAB node C from the perspective of IAB node B.Further, an MT configuration of IAB node C may include the linkdirection of a link between IAB node B and IAB node C from theperspective of IAB node C, and a DU configuration of IAB node C mayinclude link direction and availability information about a link betweena child node of IAB node C or a UE connected to IAB node C and IAB nodeC from the perspective of IAB node C.

Here, for example, an operation performed by IAB node B with respect toa child node thereof, which is IAB node C, may be referred to as a DUoperation of IAB node B. Further, an operation performed by IAB node Bwith respect to a parent node thereof, which is IAB node A, may bereferred to as an MT operation of IAB node B.

Referring to FIG. 32, a DU resource of IAB node B may refer to aresource of IAB node B for the link between IAB node B and IAB node C.The link direction and the availability of the DU resource of IAB Node Bmay be determined on the basis of the DU configuration received by IABNode B. Further, an MT resource of IAB node B may refer to a resource ofIAB node B for the link between IAB node B and IAB node A. The linkdirection of the MT resource of IAB Node B may be determined on thebasis of the MT configuration received by IAB Node B.

The above classification is only for illustration. Alternatively, from aDU perspective of an IAB node, resource types may be classified into UL,DL, F, and availability settings may be classified into NA, a hardresource, and a soft resource. In detail, the IAB node may receiveresource configuration information, and the resource configurationinformation may include link direction information and availabilityinformation. Here, the link direction information may indicate whetherthe type of a specific resource is UL, DL, or F, and the availabilityinformation may indicate whether the specific resource is a hardresource or a soft resource. Alternatively, the link directioninformation may indicate whether the type of a specific resource is UL,DL, F or NA, and the availability information may indicate whether thespecific resource is a hard resource or a soft resource.

An MT of an IAB node may be informed with a link direction configurationof a cell-specific and/or MT-specific MT. In addition, a DU may beinformed with a link direction configuration of a DU-specific and/orchild link-specific DU. Here, the link direction configuration is aconfiguration that informs whether each of resources allocated to an IABnode is a downlink (D), an uplink (U), or a flexible (F) and may also beexpressed by a resource direction configuration or a slot formatconfiguration.

Meanwhile, in NR, timing advance (TA) is calculated by the followingequation and assumes that the uplink transmission timing is advancedfrom a downlink reception timing.T _(TA)=(N _(TA) +N _(TA,offset))·T _(C)  [Equation 1]

Here, T_(C) is a basic time unit of NR, N_(TA) is a timing differencebetween downlink and uplink, and N_(TA,offset) is a fixed offset usedfor TA calculation. Meanwhile, the N_(TA) and N_(TA),offset values maybe values that the IAB node receives from its parent node or network.

Here, T_(C) is defined as T_(C)=1/(Δf_(max)·N_(f)), Δf_(max) is 480 kHz,and N_(f) is 4096.

Meanwhile, N_(TA),offset may be defined based on the following table.

TABLE 13 Frequency range and band of cell used for uplink transmissionN_(TA,offset) (unit: T_(C)) FR1 FDD band without LTE-NR 25600coexistence case or FR2 TDD band without LTE-NR coexistence case FR1 FDDband with LTE-NR coexistence 0 case FR1 TDD band with LTE-NR coexistence39936 case FR2 13792

Hereinafter, a method of synchronizing a time domain method of an IABnode proposed in the present disclosure will be described.

FIG. 33 shows an example of timing alignment in TDD based on theproposed methods of the present disclosure. In the example of FIG. 33,the parent node of FIG. 33 is an IAB node performing a DU operation onthe child node of FIG. 33, and the child node of FIG. 33 is an IAB nodeperforming an MT operation on the parent node of FIG. 33.

Referring to FIG. 33, a downlink transmission time of the parent nodeand a downlink transmission time of the child node are aligned with eachother. In addition, a time interval between an uplink reception time ofthe parent node and a downlink transmission time of the parent node maybe expressed as (N_(TA,offset)+N_(Δ))T_(C)=−2T_(Δ). In addition, a timeinterval TA between the uplink transmission time of the child node andthe downlink reception time of the child node may be expressed asN_(TA,offset)·T_(C)+2T_(P)+N_(Δ)T_(C). In this case, T_(P) is a timeinterval between the uplink transmission time of the child node and theuplink reception time of the parent node, and is a propagation delaybetween the parent node and the child node.

Meanwhile, the TΔ value is a value determined by a time required foruplink-downlink switching and/or a time required for hardwarecharacteristics, and may be a value with relatively small change.

Hereinafter, the proposed methods based on FIG. 33 will be described.That is, the following description is based on two IAB nodes. Forexample, in the following proposed method 1, the parent node is an IABnode that performs a DU operation on a child node, and conversely, thechild node is an IAB node that performs an MT operation on the parentnode. Meanwhile, it is obvious that the proposed methods of the presentdisclosure are not limited thereto.

(Proposed method 1) The child node calculates the downlink transmissiontiming by advancing it by X=TA/2+T_(Δ) from the downlink receptiontiming. Here, T=N_(Δ)T_(C). Here, in the case of the X value, the Xvalue is updated/calculated only when the TΔ value is updated/indicatedfrom the parent node, and a TA value calculated from the most recentlyreceived/updated NTA value may be used as the TA value.

FIG. 34 is a flowchart of an example of a method for updating an X valuebased on Proposed Method 1.

Referring to FIG. 34, the parent node transmits a first N_(TA) value tothe child node (S3410).

Thereafter, the parent node transmits a second N_(TA) value to the childnode (S3420).

Thereafter, the parent node transmits the T_(Δ) value to the child node(S3430).

The child node updates/calculates the X value only when the T_(Δ) valueis updated/indicated by the parent node (S3440). Here, the child nodemay use the second N_(TA) value and the T_(Δ) value whenupdating/calculating the X value.

If the child node adjusts the downlink timing whenever each of the TAvalue and the T_(Δ) value is updated, the downlink timing changes toofrequently for the child node, increasing a probability that a timingerror may occur. To prevent this, the parent node has a burden ofcontinuously measuring its downlink/uplink timing gap even whenestablishing a TA. Therefore, using the proposed method 1, it ispossible to reduce an error in the downlink timing of the child node.Here, T_(Δ) may be indicated to the child node through RRC signaling,MAC-CE signaling, or F1 Application Protocol (F1AP) signaling. Here, TAmay be defined as an interval between downlink reception timing anduplink transmission timing as shown in FIG. 33.

(Proposed method 1-1) The child node calculates the downlinktransmission timing by advancing it by X=TA/2+T_(Δ) from the downlinkreception timing. Here, T=N_(Δ)T_(C). Here, in the case of the X value,when the TA value is received from the parent node, the X value isupdated/recalculated using the most recent TA value to calculate thedownlink transmission timing. In this case, the recent TA used toupdate/recalculate the downlink transmission timing may have to existwithin a predetermined specific timing window. If there is noinformation on the new TA within the defined window, the downlinktransmission timing may be updated/recalculated using the TA that isupdated after the reception of the TΔ value, that is, the TA receivedfrom the parent node after the reception of a specific T_(Δ) or after aspecific window, and applied.

The proposed method 1-1 is an embodiment of the proposal 1, and morespecifically, is a proposal for an effective TA value for downlinktransmission timing adjustment. That is, the child node may determine,as an effective value, a TA that is agreed in advance or included in atiming window set by the parent node or the donor gNB based on the timewhen the T_(Δ) value is received, and update the downlink transmissiontiming.

FIG. 35 shows an example to which the proposed method 1-1 is applied.Here, each of (a), (b) and (c) of FIG. 35 is an example in which theproposed method 1-1 is applied according to a position of the timingwindow.

Referring to FIG. 35, a position of the timing window may be set toinclude before and after T_(Δ) reception or including T_(Δ). Here, thesize and position of the window may be previously agreed or may be setby the parent node or the donor gNB.

According to (a) of FIG. 35, TA1 included in the timing window iseffective, and the child node may update the downlink transmissiontiming based on the TA1 value. According to (b) of FIG. 35, TA2 includedin the timing window is effective, and the child node may update thedownlink transmission timing based on the TA2 value. According to (c) ofFIG. 35, since neither TA1 nor TA2 are included in the timing window,according to proposed method 1-1, the downlink transmission timing maybe updated based on TA2, which is the TA value first received after TΔis received.

Meanwhile, in the case of (b) of FIG. 35, the downlink transmissiontiming cannot be updated immediately at the time of TΔ reception, andmay be updated after waiting until TA2 is received, but if the effectiveTA2 is not received, updating cannot be performed. To this end, thedownlink transmission timing may be preferentially updated using themost recently received TA value at the T_(Δ) reception time, and thedownlink transmission timing may be updated again at the time when aneffective TA is newly received within the window of a later time point.That is, in the case of (b) of FIG. 35, at the T_(Δ) reception time, thechild node updates the downlink transmission timing based on TA1 andT_(Δ), and again at the TA2 reception time, the child node updates thedownlink transmission timing based on TA2 and T_(Δ). Alternatively, whena TA is not received within the window or when a TA or an effective TAis not received after receiving T_(Δ), the child node may perform a TAupdate request from the parent node.

(Proposed method 1-2) The child node calculates the downlinktransmission timing by advancing it by X=TA/2+T_(Δ) from the downlinkreception timing. Here, T=N_(Δ)T_(C). At this time, TA and T_(Δ)constituting the X value may be transmitted to the child node in pairsat once in the same signaling method such as RRC signaling and MAC-CEsignaling, and the child node may calculate the downlink transmissiontiming using the TA and T_(Δ) values transmitted in pairs.

The proposed method 1-2 is related to both TA and T_(Δ) in the case ofadjustment of the downlink transmission timing. In particular, theproposed method 1-2 advantageously removes ambiguity as to which valueto set/calculate based on in the process of determining the downlinktransmission timing of the child node when two values are transmittedthrough different signaling. As an example to which the proposed method1-2 is applied, a TA configured with an existing MAC-CE is not used toadjust the downlink transmission timing, but a downlink transmissiontiming may be adjusted using the value only when it isindicated/configured to the child node as a pair of (TA, T_(Δ)). As arepresentative example of the proposed method, when adjusting theoverall target timing (e.g., downlink transmission timing) whilemaintaining the uplink/downlink gap of the parent node, it is necessaryto change TA and T_(Δ), as described above, but when two values are notreceived at the same time, ambiguity about which value to follow cannotbe eliminated.

In addition, in the case of TA, for example, when the mechanism of theexisting NR is used, the TA value may be updated in the form of anaccumulation of indicated TA values. However, in this case, the TA valuebetween the parent node and the child node may be different, and thus amismatch may occur. To solve this, the TA value indicated for thepurpose of adjusting the downlink transmission timing is not indicatedas a relative value for adjusting the accumulation value, but theabsolute value of the TA may be indicated to the child node. That is, in(N_(TA,new), T_(Δ)) indicated for the purpose of adjusting the downlinktransmission timing, N_(TA,new) may be calculated by a formula (methodof calculating initial TA indicated by RAR signaling of the RACHprocedure) of N_(TA)=TA·16·64/(2^(μ)), and in this case, the granularityof the N_(TA) may be set to a value (e.g., a 12-bit value used ininitial TA setup of the RACH procedure) higher than the timinggranularity indicated by the 6-bit MAC-CE for general TA coordinationrather than the RACH procedure. If the value of (N_(TA,new), T_(Δ)) isindicated by the same container as the existing TA by MAC-CE, it isindicated using a field independent of the existing TA field, in thiscase, granularity may be different from the existing TA value.

(Proposed method 1-3) Only one value of T_(adjust)=TA/2+T_(Δ) istransmitted through RRC or MAC-CE signaling, and the downlinktransmission timing may be set by advancing by T_(adjust) from thedownlink reception timing of the IAB node. In this case, T_(adjust) usesa value having a finer granularity than TA.

The biggest feature of the method is that, the TA used in existing NR orLTE is a value advanced from the downlink reception timing and used toadjust the uplink transmission timing, and T_(adjust) is used only foradjusting the downlink transmission timing from the downlink receptiontiming as signaling separate from TA. Adjustment of the downlinktransmission timing is applied only when T_(adjust) is received, and thedownlink transmission timing is not changed due to a change in aseparate TA or downlink reception timing. As another example, theT_(adjust) value may be used for adjusting a propagation delay between achild node and a parent node.

In the case of the proposed method 1-3, fine tuning of the T_(adjust)value based on TA-closed loop between the parent node and the child nodeis indicated, that is, the parent node instructs an uplink transmissiontiming of the childe node by a TA command, and the parent nodecalculates T_(Δ) and/or T_(adjust) using the TA value calculated througha process of continuously adjusting the parent node receiving the uplinktransmission timing of the child node to which the link transmissiontiming is applied to converge to a target timing, and instructed to thechild node, thereby becoming robust to timing errors. Here, the TA valuecalculated through the above process is a value having finer granularitywhen compared with the existing TA command.

(Proposed method 1-4) The child node calculates the downlinktransmission timing by advancing it by X=TA_(avg)/2+T_(Δ,avg) from thedownlink reception timing. In this case, the T_(Δ,avg) value is afiltered (e.g., averaged) value of the past T_(Δ,avg) samplestransmitted from the parent node to the child node, and TA_(avg) is thefiltered (e.g., averaged) value of the TA samples received from thechild node.

Specifically, when the T_(Δ) sample at time t_(i) is T_(Δ)(t_(i)),T_(Δ)(t_(i)) is a value obtained by multiplying the time differencebetween the downlink transmission timing and the uplink reception timingobserved at time t_(i) in the parent node by −0.5. That is,T_(Δ)(t_(i))=−(difference value obtained by subtracting the uplinkreception timing from the downlink transmission timing observed at theparent node at the time ti)/2.

TA_(avg) may be defined by the equation below.

$\begin{matrix}{{TA}_{avg} = {\underset{i = 0}{\sum\limits^{N - 1}}{\alpha_{i}{{TA}\left( t_{i} \right)}}}} & \left\lbrack {{Equation}2} \right\rbrack\end{matrix}$

T_(Δ,avg) may be defined by the equation below.

$\begin{matrix}{T_{\Delta,{a\nu g}} = {\underset{j = 0}{\sum\limits^{M - 1}}{\beta_{j}{T_{\Delta}\left( t_{j} \right)}}}} & \left\lbrack {{Equation}3} \right\rbrack\end{matrix}$

Here, it is assumed that the number of samples of TA and T_(Δ) is N (0,. . . , N−1) and M (0, . . . , M−1), respectively. In the abovedefinition, when TA and T_(Δ) are always received/calculated together,it is regarded that M=N and H. Here, α_(i) and β_(j) may be predefinedas filter coefficients or may be signaled by a CU or a parent node to achild node. In addition, N or M values, which are filter sizes or windowsizes, may also be agreed in advance, or may be signaled by the CU orparent node to the child node. Alternatively, when the parent nodeadditionally signals values to be sampled using a bit-map or the like,the child node may use only the corresponding value for filtering. Here,as an example, α_(i)=1/N, β_(j)=1/M.

Meanwhile, in the above method, assuming that the propagation delays ofthe parent node and the child node are constant or quasi-constant, thepropagation delay TP(t_(i)) at time t_(i) has an advantage in that amore accurate TP TP(TP=TA_(avg)/2+T_(Δ,avg)) is estimated as a valueobtained by filtering using samples ofTP(t_(i))=TA(t_(i))/2+T_(Δ)(t_(i)).

Here, in a state in which the TA_(avg) value is averaged by the childnode and the T_(Δ) value is averaged by the parent node, when thedownlink transmission timing of the child node is intended to bechanged, the parent node may signal T_(Δ,avg) to the child node and thechild node may use a value obtained by adding the value to TA_(avg)/2averaged by the child node itself Through this, since the average valueis used without using a specific sample, inconsistency between the TAand T_(Δ) values can be resolved, and an accurate value robust againstnoise/error may be used. The T_(Δ) value may be signaled by RRC orMAC-CE signaling, or a CU or a parent node may select which signaling totransmit and inform the child node.

In the case of the method, since the propagation delay is calculated onthe premise that the propagation delay is constant or quasi-constant,for a transient section in which propagation delay is changed, forexample, when the IAB node moves or a blockage state occurs, sampleinput may be excluded during filtering. The parent node may recognize asa phenomenon of deviating in one direction without shaking the TA withina stable range, and the child node may determine that a TA thatincreases or decreases in one direction is received. In other words, theparent node and the child node may perform filtering under the conditionthat only samples that swing back and forth within a tolerance intervalare averaged while the TA is stable.

The method is a method of transmitting and correcting timing valuescorresponding to a state based on a premise of a fixed IAB node orassuming that the IAB node is movable but remains in a fixed state aftermovement. That is, the downlink timing may be calculated by subtractingthe TA_(avg)/2+T_(Δ,avg) value based on an instantaneous value of areception timing of a slot/symbol in which the T_(Δ) value istransmitted.

In the case of the proposed method 1-4, the X value may beupdated/recalculated only when the TΔ,avg values are updated/indicatedfrom the parent node for the X value. Alternatively, whenever the TAand/or T_(Δ,avg) values are updated, the downlink transmission timingmay be updated using samples at the corresponding time t_(i).

Meanwhile, when considering the mobile IAB node situation in which theIAB nodes are moving, a downlink reception average value (e.g., thefiltering of samples for the downlink reception timing (averagedvalue)), rather than an instantaneous downlink reception timing, may beused as a reference.

That is, whenever a TA update is transmitted, the samples at thecorresponding time t_(i) are set as input values for filtering. Theparent node calculates TA_(avg), and the child node calculates T_(Δ,avg)values and the downlink reception average value, and then downlinktransmission timing at the time of the transmission timing change may becalculated/applied as a value obtained by subtracting the TA_(avg)/2 andT_(Δ,avg) values from the downlink reception average value (i.e.,DL_RX_(abg)−TA_(avg)/2−T_(Δ,avg)). Here, the downlink reception averagevalue (DL_RX_(avg)) may be calculated based on the following equation.

$\begin{matrix}{{DL\_ RX}_{a\nu g} = {\underset{i = 0}{\sum\limits^{N - 1}}{\gamma_{i}{DL\_ RX}\left( t_{i} \right)}}} & \left\lbrack {{Equation}4} \right\rbrack\end{matrix}$

Here, γ_(i) is a coefficient of the filter.

In this case, all samples corresponding to TA updates may be used asfiltering inputs even if TA, T_(Δ), and downlink reception timing areunstable. That is, in this case, the downlink transmission timing may bedirectly estimated based on TA_(avg) and T_(Δ,avg) based on DL_RX_(avg).

As a case in which filtering such as average needs to be reset andrestarted, there may be cases where the parent node changes its downlinktiming, and while maintaining the downlink timing, an average value maybe calculated using consistent filtering regardless of changes in TP,TA, and T_(Δ) as input. Based on this, the following method is proposed.

(Proposed method 1-5) Like a mobile IAB node, when there is movement ofthe IAB node or when the channel environment is changed, the child nodemay calculate by advancing the downlink transmission timing byX(X=TA_(avg)/2+T_(Δ,avg)) from the downlink reception timing.

The CU or the parent node may instruct the child node which method touse among the Proposed Methods 1-4 and the Proposed Methods 1-5 based onthe channel environment or the capability of the IAB node.

Meanwhile, the downlink transmission timing for a given time may becalculated as follows.

$\begin{matrix}{{{DL\_ TX}(t)} = {{{DL\_ RX}(t)} - \frac{T{A(t)}}{2} - {T_{\Delta}(t)}}} & \left\lbrack {{Equation}5} \right\rbrack\end{matrix}$

For the above equation, an actual TA(t) value used by the child node isTA(t)=DL_RX(t)−UL_TX(t). Here, UL_TX(t) is a timing at which the UEperforms uplink transmission by reflecting the actual TA. That is, theTA command is derived to a target timing set by the parent node, but isestablished in reality, by the actual TA(t) at the transmission time t,that is, a difference value obtained by subtracting the transmissiontiming from the downlink reception timing at the IAB node MT at the timet.

Therefore, when the actual TA (TA_(actual)) is reflected in the aboveequation, the following equation is obtained.

$\begin{matrix}{{{DL\_ TX}(t)} = {{\frac{1}{2} \cdot \left\lbrack {{{DL\_ RX}(t)} + {{UL\_ TX}(t)}} \right\rbrack} - {T_{\Delta}(t)}}} & \left\lbrack {{Equation}6} \right\rbrack\end{matrix}$

In other words, since the TA command does not play a role in the actualvalid expression in the child node, the operation to use the parametermay not be appropriate. Interpreting Equation 6 above, a median value ofan uplink transmission timing of the IAB node at the uplink transmissiontime t, which is actual values that the IAB node may always record(e.g., the value stored in the buffer to take a filter such as theaverage, as in the proposed methods) and a downlink reception timing(observed at the same time t as the transmission time in mostimplementations) used as a reference to obtain a transmission timingthereof, that is, [DL_RX(t)+UL_TX(t)]/2 may be calculated, and T_(Δ)(t)(generally a negative value) may be subtracted therefrom to obtain adownlink transmission timing.

When the above equation is extended to a mobile IAB node or a mobilerelay, the average or low-pass filtered operation (expressed as asubscript avg in Equation 7 below) may be taken as it is, as in ProposedMethods 1 to 1-5. Therefore, it may be expressed as the followingequation.

$\begin{matrix}\begin{matrix}{{DL\_ TXextim}_{ate} = {{DL\_ TXavg}(t)}} \\{= {\frac{1}{2} \cdot \left\lbrack {{{DL\_ RXavg}(t)} + {{UL\_ TXavg}(t)}} \right\rbrack}} \\{- {T_{\Delta,{avg}}(t)}}\end{matrix} & \left\lbrack {{Equation}7} \right\rbrack\end{matrix}$

Therefore, the IAB node filters and records the median values of theuplink transmission timing and the downlink reception timing, and theparent node filters and records the T_(Δ)(t) observed by itself andtransmits it to the IAB node at a required time. Then, the IAB node mayobtain a downlink transmission estimation value (DL_TX_(estimate)) usingthe Equation.

Meanwhile, even if the IAB node records and has DL_RX_(avg)(t) andUL_TX_(avg)(t) separately and combines the values, since averaging orfiltering is a linear operation, the downlink transmission estimationvalue may estimate a downlink transmission timing equally based onEquation 7 above.

In general, filtering may set an arbitrary length within a section inwhich the parent node does not change the downlink transmission timingby itself. Therefore, when the parent node changes its downlinktransmission timing, the parent node takes filtering until a stable newT_(Δ,avg)(t) is obtained, and transmits the new T_(Δ,avg)(t) to thechild node, and the child node may continue filtering for an arbitrarytime until it receives a new value, and when a new T_(Δ,avg)(t) isreceived, the child node may reset the filtered values and newly performall filtering operations.

In addition, an operation informing the parent node to take filteringfor a specific period may be applied. Alternatively, the IAB node may besignaled to reset the filter through a flag at a timing of changing thedownlink transmission timing.

(Proposed method 2) The child node reports the currentTA_(child)-related information or NTA,_(child)-related informationcalculated as information on the N_(TA) instructed/configured by theparent node to the parent node.

One of the causes of the mismatch in downlink timing between the childnode and the parent node is that N_(TA)-related information possessed bythe parent node and the child node may be different from each other. Asshown in Equation 8 below, since the latest value of the N_(TA) appliedby the child node or the terminal is an accumulated value of N_(TA)values indicated by the parent node or the base station, if the childnode or the terminal misses the information or due to a detection error,etc., the N_(TA)-related information possessed by the parent node andchild node has may be different from each other.T _(A new) =N _(TA old)+(T _(A)−31)·16·64/2^(μ)  [Equation 8]

Therefore, an error may occur in the calculation of downlink timingadvancing information (i.e., TA/2+T_(Δ)) of the child node calculatedbased on this. In order to solve this problem, the child node may reportto the parent node the latest N_(TA),child related information orTA_(child) value calculated based on the information indicated by thechild node from the base station. Here, a term in which child is addedas a subscript means a term related to a child node.

FIG. 36 is a diagram for an example of an operation between a parentnode and a child node based on the proposed method 2.

Referring to FIG. 36, the parent node transmits a first N_(TA) value tothe child node (S3610). In addition, the parent node transmits thesecond N_(TA) value to the child node (S3620). Here, in FIG. 36, it isassumed that the child node does not detect the second N_(TA) value.

Thereafter, the child node calculates TA_(child) or N_(TA,child) basedon the first N_(TA) value (S3630). Thereafter, the child node transmitsthe calculated TA_(child) or N_(TA,child) to the parent node (S3640).

The parent node receiving the TA_(child) or N_(TA,child) calculated bythe child node determines a downlink timing error based on thecalculated TA_(child) or NTA,_(child) and adjusts a downlink timing(S3650).

(Suggested method 2-1) If the child node has its own timing source, suchas a global navigation satellite system (GNSS), the downlinktransmission timing update may not be necessary, so that the child nodemay request omission of T_(Δ) information transmission from the parentnode or a doner node and may not expect the indication/setting of T_(Δ)information from the parent node. Even if the corresponding informationis transmitted from the parent node, the child node may ignore thecorresponding information.

(Proposed method 3) When the downlink reception timing of the child nodeis changed due to a change in the downlink transmission timing of theparent node, the following options may be considered for the downlinktransmission timing of the child node.

-   -   Option 1: When the downlink reception timing of the child node        is changed and a new TA and/or T_(Δ) value is not indicated from        the parent node, the child node does not change the downlink        transmission timing and maintains the existing downlink        transmission timing.    -   Option 2: When a downlink reception timing of the child node is        changed, the downlink transmission timing of the child node is        always determined by [downlink reception timing−TA/2−T_(Δ)],        where TA and T_(Δ) is calculated as values most recently        transmitted from the parent node.    -   Option 3: If the downlink reception timing measured by the child        node does not deviate by more than a specific threshold and the        TA and/or T_(Δ) values are not indicated/set by the parent node,        the child node does not change the downlink timing and maintains        the existing downlink transmission timing.

FIG. 37 is a flowchart for an example of a synchronization method for aDU transmission timing performed by an IAB node according to someimplementations of the present disclosure.

Referring to FIG. 37, an IAB node performs a random access operation(S3710). The random access operation may include operations oftransmitting a random access request signal to a base station or aparent node and receiving a random access response signal from the basestation or the parent node.

The IAB node receives a first parameter and a second parameter from theparent node (S3720). Here, the first parameter may be related an MTtransmission timing of the IAB node, and the second parameter may berelated to the DU transmission timing of the IAB node.

Thereafter, the IAB node determines a time spacing between an MTreception timing and the DU transmission timing of the IAB node based onthe first parameter and the second parameter (S3730).

Later, the IAB node performs synchronization for the DU transmissiontiming with the parent node based on the time spacing (S3740). That is,the time spacing may be identical to the timing spacing between the DUtransmission timing of the parent node and the MT reception timing ofthe IAB node. Here, the IAB node may perform synchronization for the DUtransmission timing by synchronize the DU transmission timing of theparent node with its own DU transmission timing.

In addition, here, the second parameter may be T_(Δ) described above,and the first parameter may be N_(TA) described above.

Meanwhile, although it is not shown in FIG. 37, the example of FIG. 37may be an example to which at least one of the proposed methods describeabove is applied.

The claims described in the present disclosure may be combined invarious ways. For example, the technical features of the method claimsof the present disclosure may be combined to be implemented as anapparatus, and the technical features of the apparatus claims of thepresent disclosure may be combined to be implemented as a method. Inaddition, the technical features of the method claim of the presentdisclosure and the technical features of the apparatus claim may becombined to be implemented as an apparatus, and the technical featuresof the method claim of the present disclosure and the technical featuresof the apparatus claim may be combined to be implemented as a method.

The methods proposed in the present disclosure may be executableconnected to at least one computer readable medium including aninstruction based on the execution by at least one processor, one ormore processors, and one or more memories executable connected to theprocessor and storing instructions, except an IAB node. The one or moreprocessors may also be executed by an apparatus configured to control anIAB node, which executes the instructions and performs the methodsproposed in the present disclosure.

Hereinafter, the random access will be described. a part or the wholeprocedures described below may be performed in step S3710 of FIG. 37.

The random access procedure may be summarized as the following table.

TABLE 14 Type of signal Operation/obtained information Step 1 PRACHpreamble Initial beam acquisition, random election of UL of RA-preambleID Step 2 Random access Timing arrangement information, RA- response onpreamble ID, initial UL grant, temporal DL-SCH C-RNTI Step 3 ULtransmission on RRC connection request, UE identifier UL-SCH Step 4Contention C-RNTI on PDCCH for initial access, resolution C-RNTI onPDCCH for UE in of DL RRC_CONNECTED state

FIG. 38 is illustrated to describe the random access procedure.

Referring to FIG. 38, first, the UE may transmit a PRACH preamble to ULas Msg 1 of the random access procedure.

The random access preamble sequence having two different lengths issupported. The long sequence of length 839 is applied to the subcarrierspacing of 1.25 kHz and 5 kHz, and the short sequence of length 139 isapplied to the subcarrier spacing of 15, 30, 60, and 120 kHz. The longsequence supports an unrestricted set and a restricted set of type A andtype B. On the other hand, the short sequence supports only anunrestricted set.

A plurality of RACH preamble formats is defined by one or more RACH OFDMsymbols, different cyclic prefixes (CPs), and a guard time. The PRACHpreamble configuration to be used is provided to the UE as systeminformation.

In the case that there is no response to Msg 1, the UE may retransmitthe PRACH preamble which is power-lamped within a predetermined count.The UE calculates the PRACH transmission power for the retransmission ofthe preamble based on the latest estimated path loss and the powertamping counter. When the UE performs a beam switching, the powerTamping counter does not change.

Hereinafter, an example of a communication system to which thedisclosure is applied is described.

Various descriptions, functions, procedures, proposals, methods, and/oroperational flowcharts disclosed herein may be applied to, but notlimited to, various fields requiring wireless communication/connection(e.g., 5G) between devices.

Hereinafter, specific examples are illustrated with reference todrawings. In the following drawings/description, unless otherwiseindicated, like reference numerals may refer to like or correspondinghardware blocks, software blocks, or functional blocks.

FIG. 39 illustrates a communication system 1 applied to the disclosure.

Referring to FIG. 39, the communication system 1 applied to thedisclosure includes a wireless device, a base station, and a network.Here, the wireless device refers to a device that performs communicationusing a radio access technology (e.g., 5G new RAT (NR) or Long-TermEvolution (LTE)) and may be referred to as a communication/wireless/5Gdevice. The wireless device may include, but limited to, a robot 100 a,a vehicle 100 b-1 and 100 b-2, an extended reality (XR) device 100 c, ahand-held device 100 d, a home appliance 100 e, an Internet of things(IoT) device 100 f, and an AI device/server 400. For example, thevehicle may include a vehicle having a wireless communication function,an autonomous driving vehicle, a vehicle capable of inter-vehiclecommunication, or the like. Here, the vehicle may include an unmannedaerial vehicle (UAV) (e.g., a drone). The XR device may includeaugmented reality (AR)/virtual reality (VR)/mixed reality (MR) devicesand may be configured as a head-mounted device (HMD), a vehicularhead-up display (HUD), a television, a smartphone, a computer, awearable device, a home appliance, digital signage, a vehicle, a robot,or the like. The hand-held device may include a smartphone, a smartpad,a wearable device (e.g., a smart watch or smart glasses), and a computer(e.g., a notebook). The home appliance may include a TV, a refrigerator,a washing machine, and the like. The IoT device may include a sensor, asmart meter, and the like. The base station and the network may beconfigured, for example, as wireless devices, and a specific wirelessdevice 200 a may operate as a base station/network node for otherwireless devices.

Here, the wireless communication technology implemented in the wirelessdevice of the present disclosure may include a narrowband Internet ofThings for low-power communication as well as LTE, NR, and 6G. At thistime, for example, NB-IoT technology may be an example of low power widearea network (LPWAN) technology, and may be implemented in standardssuch as LTE Cat NB1 and/or LTE Cat NB2, may be implemented in thestandard of LTE Cat NB1 and/or LTE Cat NB2, and is not limited to thenames mentioned above. Additionally or alternatively, the wirelesscommunication technology implemented in the wireless device of thepresent disclosure may perform communication based on LTE-M technology.In this case, as an example, the LTE-M technology may be an example ofan LPWAN technology, and may be called by various names such as enhancedmachine type communication (eMTC). For example, LTE-M technology may beimplemented by at least any one of various standards such as 1) LTE CAT0, 2) LTE Cat M1, 3) LTE Cat M2, 4) LTE non-BL (non-Bandwidth Limited),5) LTE-MTC, 6) LTE Machine Type Communication, and/or 7) LTE M, and isnot limited to the names described above. Additionally or alternatively,the wireless communication technology implemented in the wireless deviceof the present disclosure may include at least one of ZigBee, Bluetooth,and LPWAN considering low power communication and is not limited to thenames described above. For example, the ZigBee technology may createpersonal area networks (PAN) related to small/low-power digitalcommunication based on various standards such as IEEE 802.15.4, and maybe called by various names.

The wireless devices 100 a to 100 f may be connected to the network 300through the base station 200. Artificial intelligence (AI) technologymay be applied to the wireless devices 100 a to 100 f, and the wirelessdevices 100 a to 100 f may be connected to an AI server 400 through thenetwork 300. The network 300 may be configured using a 3G network, a 4G(e.g., LTE) network, or a 5G (e.g., NR) network. The wireless devices100 a to 100 f may communicate with each other via the base station200/network 300 and may also perform direct communication (e.g. sidelinkcommunication) with each other without passing through the basestation/network. For example, the vehicles 100 b-1 and 100 b-2 mayperform direct communication (e.g. vehicle-to-vehicle(V2V)/vehicle-to-everything (V2X) communication). Further, the IoTdevice (e.g., a sensor) may directly communicate with another IoT device(e.g., a sensor) or another wireless device 100 a to 100 f.

Wireless communications/connections 150 a, 150 b, and 150 c may beestablished between the wireless devices 100 a to 100 f and the basestation 200 and between the base stations 200. Here, the wirelesscommunications/connections may be established by various wireless accesstechnologies (e.g., 5G NR), such as uplink/downlink communication 150 a,sidelink communication 150 b (or D2D communication), and inter-basestation communication 150 c (e.g., relay or integrated access backhaul(IAB)). The wireless devices and the base station/wireless devices, andthe base stations may transmit/receive radio signals to/from each otherthrough the wireless communications/connections 150 a, 150 b, and 150 c.For example, the wireless communications/connections 150 a, 150 b, and150 c may transmit/receive signals over various physical channels. Tothis end, at least some of various configuration information settingprocesses, various signal processing processes (e.g., channelencoding/decoding, modulation/demodulation, resource mapping/demapping,and the like), and resource allocation processes may be performed on thebasis of various proposals of the disclosure.

FIG. 40 illustrates a wireless device that is applicable to thedisclosure.

Referring to FIG. 40, a first wireless device 100 and a second wirelessdevice 200 may transmit and receive radio signals through various radioaccess technologies (e.g., LTE and NR). Here, the first wireless device100 and the second wireless device 200 may respectively correspond to awireless device 100 x and the base station 200 of FIG. 39 and/or mayrespectively correspond to a wireless device 100 x and a wireless device100 x of FIG. 39.

The first wireless device 100 includes at least one processor 102 and atleast one memory 104 and may further include at least one transceiver106 and/or at least one antenna 108. The processor 102 may be configuredto control the memory 104 and/or the transceiver 106 and to implementthe descriptions, functions, procedures, proposals, methods, and/oroperational flowcharts disclosed herein. For example, the processor 102may process information in the memory 104 to generate firstinformation/signal and may then transmit a radio signal including thefirst information/signal through the transceiver 106. In addition, theprocessor 102 may receive a radio signal including secondinformation/signal through the transceiver 106 and may store informationobtained from signal processing of the second information/signal in thememory 104. The memory 104 may be connected to the processor 102 and maystore various pieces of information related to the operation of theprocessor 102. For example, the memory 104 may store a software codeincluding instructions to perform some or all of processes controlled bythe processor 102 or to perform the descriptions, functions, procedures,proposals, methods, and/or operational flowcharts disclosed herein.Here, the processor 102 and the memory 104 may be part of acommunication modem/circuit/chip designed to implement a radiocommunication technology (e.g., LTE or NR). The transceiver 106 may beconnected with the processor 102 and may transmit and/or receive a radiosignal via the at least one antennas 108. The transceiver 106 mayinclude a transmitter and/or a receiver. The transceiver 106 may bereplaced with a radio frequency (RF) unit. In the disclosure, thewireless device may refer to a communication modem/circuit/chip.

The second wireless device 200 includes at least one processor 202 andat least one memory 204 and may further include at least one transceiver206 and/or at least one antenna 208. The processor 202 may be configuredto control the memory 204 and/or the transceiver 206 and to implementthe descriptions, functions, procedures, proposals, methods, and/oroperational flowcharts disclosed herein. For example, the processor 202may process information in the memory 204 to generate thirdinformation/signal and may then transmit a radio signal including thethird information/signal through the transceiver 206. In addition, theprocessor 202 may receive a radio signal including fourthinformation/signal through the transceiver 206 and may store informationobtained from signal processing of the fourth information/signal in thememory 204. The memory 204 may be connected to the processor 202 and maystore various pieces of information related to the operation of theprocessor 202. For example, the memory 204 may store a software codeincluding instructions to perform some or all of processes controlled bythe processor 202 or to perform the descriptions, functions, procedures,proposals, methods, and/or operational flowcharts disclosed herein.Here, the processor 202 and the memory 204 may be part of acommunication modem/circuit/chip designed to implement a radiocommunication technology (e.g., LTE or NR). The transceiver 206 may beconnected with the processor 202 and may transmit and/or receive a radiosignal via the at least one antennas 208. The transceiver 206 mayinclude a transmitter and/or a receiver. The transceiver 206 may bereplaced with an RF unit. In the disclosure, the wireless device mayrefer to a communication modem/circuit/chip.

Hereinafter, hardware elements of the wireless devices 100 and 200 aredescribed in detail. At least one protocol layer may be implemented, butlimited to, by the at least one processor 102 and 202. For example, theat least one processor 102 and 202 may implement at least one layer(e.g., a functional layer, such as PHY, MAC, RLC, PDCP, RRC, and SDAPlayers). The at least one processor 102 and 202 may generate at leastone protocol data unit (PDU) and/or at least one service data unit (SDU)according to the descriptions, functions, procedures, proposals,methods, and/or operational flowcharts disclosed herein. The at leastone processor 102 and 202 may generate a message, control information,data, or information according to the descriptions, functions,procedures, proposals, methods, and/or operational flowcharts disclosedherein. The at least one processor 102 and 202 may generate a signal(e.g., a baseband signal) including a PDU, an SDU, a message, controlinformation, data, or information according to the functions,procedures, proposals, and/or methods disclosed herein and may providethe signal to the at least one transceiver 106 and 206. The at least oneprocessor 102 and 202 may receive a signal (e.g., a baseband signal)from the at least one transceiver 106 and 206 and may obtain a PDU, anSDU, a message, control information, data, or information according tothe descriptions, functions, procedures, proposals, methods, and/oroperational flowcharts disclosed herein.

The at least one processor 102 and 202 may be referred to as acontroller, a microcontroller, a microprocessor, or a microcomputer. Theat least one processor 102 and 202 may be implemented by hardware,firmware, software, or a combination thereof. For example, at least oneapplication-specific integrated circuit (ASIC), at least one digitalsignal processor (DSP), at least one digital signal processing devices(DSPD), at least one programmable logic devices (PLD), or at least onefield programmable gate array (FPGA) may be included in the at least oneprocessor 102 and 202. The descriptions, functions, procedures,proposals, methods, and/or operational flowcharts disclosed herein maybe implemented using firmware or software, and the firmware or softwaremay be configured to include modules, procedures, functions, and thelike. The firmware or software configured to perform the descriptions,functions, procedures, proposals, methods, and/or operational flowchartsdisclosed herein may be included in the at least one processor 102 and202 or may be stored in the at least one memory 104 and 204 and may beexecuted by the at least one processor 102 and 202. The descriptions,functions, procedures, proposals, methods, and/or operational flowchartsdisclosed herein may be implemented in the form of a code, aninstruction, and/or a set of instructions using firmware or software.

The at least one memory 104 and 204 may be connected to the at least oneprocessor 102 and 202 and may store various forms of data, signals,messages, information, programs, codes, indications, and/or commands.The at least one memory 104 and 204 may be configured as a ROM, a RAM,an EPROM, a flash memory, a hard drive, a register, a cache memory, acomputer-readable storage medium, and/or a combinations thereof. The atleast one memory 104 and 204 may be disposed inside and/or outside theat least one processor 102 and 202. In addition, the at least one memory104 and 204 may be connected to the at least one processor 102 and 202through various techniques, such as a wired or wireless connection.

The at least one transceiver 106 and 206 may transmit user data, controlinformation, a radio signal/channel, or the like mentioned in themethods and/or operational flowcharts disclosed herein to at leastdifferent device. The at least one transceiver 106 and 206 may receiveuser data, control information, a radio signal/channel, or the likementioned in the descriptions, functions, procedures, proposals,methods, and/or operational flowcharts disclosed herein from at leastone different device. For example, the at least one transceiver 106 and206 may be connected to the at least one processor 102 and 202 and maytransmit and receive a radio signal. For example, the at least oneprocessor 102 and 202 may control the at least one transceiver 106 and206 to transmit user data, control information, or a radio signal to atleast one different device. In addition, the at least one processor 102and 202 may control the at least one transceiver 106 and 206 to receiveuser data, control information, or a radio signal from at least onedifferent device. The at least one transceiver 106 and 206 may beconnected to the at least one antenna 108 and 208 and may be configuredto transmit or receive user data, control information, a radiosignal/channel, or the like mentioned in the descriptions, functions,procedures, proposals, methods, and/or operational flowcharts disclosedherein through the at least one antenna 108 and 208. In this document,the at least one antenna may be a plurality of physical antennas or maybe a plurality of logical antennas (e.g., antenna ports). The at leastone transceiver 106 and 206 may convert a received radio signal/channelfrom an RF band signal into a baseband signal in order to processreceived user data, control information, a radio signal/channel, or thelike using the at least one processor 102 and 202. The at least onetransceiver 106 and 206 may convert user data, control information, aradio signal/channel, or the like, processed using the at least oneprocessor 102 and 202, from a baseband signal to an RF bad signal. Tothis end, the at least one transceiver 106 and 206 may include an(analog) oscillator and/or a filter.

FIG. 41 illustrates a signal processing circuit for a transmissionsignal.

Referring to FIG. 41, the signal processing circuit 1000 may include ascrambler 1010, a modulator 1020, a layer mapper 1030, a precoder 1040,a resource mapper 1050, and a signal generator 1060.Operations/functions illustrated with reference to FIG. 41 may beperformed, but not limited to, in the processor 102 and 202 and/or thetransceiver 106 and 206 of FIG. 40. Hardware elements illustrated inFIG. 41 may be configured in the processor 102 and 202 and/or thetransceiver 106 and 206 of FIG. 40. For example, blocks 1010 to 1060 maybe configured in the processor 102 and 202 of FIG. 40. Alternatively,blocks 1010 to 1050 may be configured in the processor 102 and 202 ofFIG. 40, and a block 1060 may be configured in the transceiver 106 and206 of FIG. 40.

A codeword may be converted into a radio signal via the signalprocessing circuit 1000 of FIG. 41. Here, the codeword is an encoded bitsequence of an information block. The information block may include atransport block (e.g., a UL-SCH transport block and a DL-SCH transportblock). The radio signal may be transmitted through various physicalchannels (e.g., a PUSCH or a PDSCH).

Specifically, the codeword may be converted into a scrambled bitsequence by the scrambler 1010. A scrambled sequence used for scramblingis generated on the basis of an initialization value, and theinitialization value may include ID information about a wireless device.The scrambled bit sequence may be modulated into a modulation symbolsequence by the modulator 1020. A modulation scheme may includepi/2-binary phase shift keying (pi/2-BPSK), m-phase shift keying(m-PSK), m-quadrature amplitude modulation (m-QAM), and the like. Acomplex modulation symbol sequence may be mapped to at least onetransport layer by the layer mapper 1030. Modulation symbols of eachtransport layer may be mapped to a corresponding antenna port(s) by theprecoder 1040 (precoding). Output z from the precoder 1040 may beobtained by multiplying output y from the layer mapper 1030 by aprecoding matrix W of N*M, where N is the number of antenna ports, and Mis the number of transport layers. Here, the precoder 1040 may performprecoding after performing transform precoding (e.g., DFT transform) oncomplex modulation symbols. Alternatively, the precoder 1040 may performprecoding without performing transform precoding.

The resource mapper 1050 may map a modulation symbol of each antennaport to a time-frequency resource. The time-frequency resource mayinclude a plurality of symbols (e.g., CP-OFDMA symbols or DFT-s-OFDMAsymbols) in the time domain and may include a plurality of subcarriersin the frequency domain. The signal generator 1060 may generate a radiosignal from mapped modulation symbols, and the generated radio signalmay be transmitted to another device through each antenna. To this end,the signal generator 1060 may include an inverse fast Fourier transform(IFFT) module, a cyclic prefix (CP) inserter, a digital-to-analogconverter (DAC), a frequency upconverter, and the like.

A signal processing procedure for a received signal in a wireless devicemay be performed in the reverse order of the signal processing procedure1010 to 1060 of FIG. 41. For example, a wireless device (e.g., 100 and200 of FIG. 40) may receive a radio signal from the outside through anantenna port/transceiver. The received radio signal may be convertedinto a baseband signal through a signal reconstructor. To this end, thesignal reconstructor may include a frequency downconverter, ananalog-to-digital converter (ADC), a CP remover, and a fast Fouriertransform (FFT) module. The baseband signal may be reconstructed to acodeword through resource demapping, postcoding, demodulation, anddescrambling. The codeword may be reconstructed to an originalinformation block through decoding. Thus, a signal processing circuit(not shown) for a received signal may include a signal reconstructor, aresource demapper, a postcoder, a demodulator, a descrambler and adecoder.

FIG. 42 illustrates another example of a wireless device applied to thedisclosure. The wireless device may be configured in various formsdepending on usage/service.

Referring to FIG. 42, the wireless devices 100 and 200 may correspond tothe wireless device 100 and 200 of FIG. 40 and may include variouselements, components, units, and/or modules. For example, the wirelessdevice 100 and 200 may include a communication unit 110, a control unit120, a memory unit 130, and additional components 140. The communicationunit may include a communication circuit 112 and a transceiver(s) 114.For example, the communication circuit 112 may include the at least oneprocessor 102 and 202 and/or the at least one memory 104 and 204 of FIG.40. For example, the transceiver(s) 114 may include the at least onetransceiver 106 and 206 and/or the at least one antenna 108 and 208 ofFIG. 40. The control unit 120 is electrically connected to thecommunication unit 110, the memory unit 130, and the additionalcomponents 140 and controls overall operations of the wireless device.For example, the control unit 120 may control electrical/mechanicaloperations of the wireless device on the basis of aprogram/code/command/information stored in the memory unit 130. Inaddition, the control unit 120 may transmit information stored in thememory unit 130 to the outside (e.g., a different communication device)through a wireless/wired interface via the communication unit 110 or maystore, in the memory unit 130, information received from the outside(e.g., a different communication device) through the wireless/wiredinterface via the communication unit 110.

The additional components 140 may be configured variously depending onthe type of the wireless device. For example, the additional components140 may include at least one of a power unit/battery, an input/output(I/O) unit, a driving unit, and a computing unit. The wireless devicemay be configured, but not limited to, as a robot (100 a in FIG. 39), avehicle (100 b-1 or 100 b-2 in FIG. 39), an XR device (100 c in FIG.39), a hand-held device (100 d in FIG. 39), a home appliance (100 e inFIG. 39), an IoT device (100 f in FIG. 39), a terminal for digitalbroadcasting, a hologram device, a public safety device, an MTC device,a medical device, a fintech device (or financial device), a securitydevice, a climate/environmental device, an AI server/device (400 in FIG.39), a base station (200 in FIG. 39), a network node, or the like. Thewireless device may be mobile or may be used in a fixed place dependingon usage/service.

In FIG. 42, all of the various elements, components, units, and/ormodules in the wireless devices 100 and 200 may be connected to eachother through a wired interface, or at least some thereof may bewirelessly connected through the communication unit 110. For example,the control unit 120 and the communication unit 110 may be connected viaa cable in the wireless device 100 and 200, and the control unit 120 anda first unit (e.g., 130 and 140) may be wirelessly connected through thecommunication unit 110. In addition, each element, component, unit,and/or module in wireless device 100 and 200 may further include atleast one element. For example, the control unit 120 may include atleast one processor set. For example, the control unit 120 may beconfigured as a set of a communication control processor, an applicationprocessor, an electronic control unit (ECU), a graphics processingprocessor, a memory control processor, and the like. In another example,the memory unit 130 may include a random-access memory (RAM), a dynamicRAM (DRAM), a read-only memory (ROM), a flash memory, a volatile memory,a non-volatile memory, and/or a combination thereof.

Next, an illustrative configuration of FIG. 42 is described in detailwith reference to the accompanying drawing.

FIG. 43 illustrates a hand-held device applied to the disclosure. Thehand-held device may include a smartphone, a smartpad, a wearable device(e.g., a smart watch or smart glasses), and a portable computer (e.g., anotebook). The hand-held device may be referred to as a mobile station(MS), a user terminal (UT), a mobile subscriber station (MSS), asubscriber station (SS), an advanced mobile station (AMS), or a wirelessterminal (WT).

Referring to FIG. 43, the hand-held device 100 may include an antennaunit 108, a communication unit 110, a control unit 120, a memory unit130, a power supply unit 140 a, an interface unit 140 b, and aninput/output unit 140 c. The antenna unit 108 may be configured as apart of the communication unit 110. Blocks 110 to 130/140 a to 140 ccorrespond to the blocks 110 to 130/140 in FIG. 42, respectively.

The communication unit 110 may transmit and receive a signal (e.g.,data, a control signal, or the like) to and from other wireless devicesand base stations. The control unit 120 may control various componentsof the hand-held device 100 to perform various operations. The controlunit 120 may include an application processor (AP). The memory unit 130may store data/parameter/program/code/command necessary to drive thehand-held device 100. Further, the memory unit 130 may storeinput/output data/information. The power supply unit 140 a suppliespower to the hand-held device 100 and may include a wired/wirelesscharging circuit, a battery, and the like. The interface unit 140 b maysupport a connection between the hand-held device 100 and a differentexternal device. The interface unit 140 b may include various ports(e.g., an audio input/output port and a video input/output port) forconnection to an external device. The input/output unit 140 c mayreceive or output image information/signal, audio information/signal,data, and/or information input from a user. The input/output unit 140 cmay include a camera, a microphone, a user input unit, a display unit140 d, a speaker, and/or a haptic module.

For example, in data communication, the input/output unit 140 c mayobtain information/signal (e.g., a touch, text, voice, an image, and avideo) input from the user, and the obtained information/signal may bestored in the memory unit 130. The communication unit 110 may convertinformation/signal stored in the memory unit into a radio signal and maytransmit the converted radio signal directly to a different wirelessdevice or to a base station. In addition, the communication unit 110 mayreceive a radio signal from a different wireless device or the basestation and may reconstruct the received radio signal to originalinformation/signal. The reconstructed information/signal may be storedin the memory unit 130 and may then be output in various forms (e.g.,text, voice, an image, a video, and a haptic form) through theinput/output unit 140 c.

FIG. 44 illustrates a vehicle or an autonomous driving vehicle appliedto the disclosure. The vehicle or the autonomous driving may beconfigured as a mobile robot, a car, a train, a manned/unmanned aerialvehicle (AV), a ship, or the like.

Referring to FIG. 44, the vehicle or the autonomous driving vehicle 100may include an antenna unit 108, a communication unit 110, a controlunit 120, a driving unit 140 a, a power supply unit 140 b, a sensor unit140 c, and an autonomous driving unit 140 d. The antenna unit 108 may beconfigured as a part of the communication unit 110. Blocks 110/130/140 ato 140 d correspond to the blocks 110/130/140 in FIG. 42, respectively.

The communication unit 110 may transmit and receive a signal (e.g.,data, a control signal, or the like) to and from external devices, suchas a different vehicle, a base station (e.g. a base station, a road-sideunit, or the like), and a server. The control unit 120 may controlelements of the vehicle or the autonomous driving vehicle 100 to performvarious operations. The control unit 120 may include an electroniccontrol unit (ECU). The driving unit 140 a may enable the vehicle or theautonomous driving vehicle 100 to run on the ground. The driving unit140 a may include an engine, a motor, a power train, wheels, a brake, asteering device, and the like. The power supply unit 140 b suppliespower to the vehicle or the autonomous driving vehicle 100 and mayinclude a wired/wireless charging circuit, a battery, and the like. Thesensor unit 140 c may obtain a vehicle condition, environmentalinformation, user information, and the like. The sensor unit 140 c mayinclude an inertial measurement unit (IMU) sensor, a collision sensor, awheel sensor, a speed sensor, an inclination sensor, a weight sensor, aheading sensor, a position module, vehicular forward/backward visionsensors, a battery sensor, a fuel sensor, a tire sensor, a steeringsensor, a temperature sensor, a humidity sensor, an ultrasonic sensor,an illuminance sensor, a pedal position sensor, and the like. Theautonomous driving unit 140 d may implement a technology for maintaininga driving lane, a technology for automatically adjusting speed, such asadaptive cruise control, a technology for automatic driving along a setroute, a technology for automatically setting a route and driving when adestination is set, and the like.

For example, the communication unit 110 may receive map data, trafficcondition data, and the like from an external server. The autonomousdriving unit 140 d may generate an autonomous driving route and adriving plan on the basis of obtained data. The control unit 120 maycontrol the driving unit 140 a to move the vehicle or the autonomousdriving vehicle 100 along the autonomous driving route according to thedriving plan (e.g., speed/direction control). During autonomous driving,the communication unit 110 may aperiodically/periodically obtain updatedtraffic condition data from the external server and may obtainsurrounding traffic condition data from a neighboring vehicle. Further,during autonomous driving, the sensor unit 140 c may obtain a vehiclecondition and environmental information. The autonomous driving unit 140d may update the autonomous driving route and the driving plan on thebasis of newly obtained data/information. The communication unit 110 maytransmit information about a vehicle location, an autonomous drivingroute, a driving plan, and the like to the external server. The externalserver may predict traffic condition data in advance using AI technologyor the like on the basis of information collected from vehicles orautonomous driving vehicles and may provide the predicted trafficcondition data to the vehicles or the autonomous driving vehicles.

FIG. 45 illustrates a vehicle applied to the disclosure. The vehicle maybe implemented as a means of transportation, a train, an air vehicle, aship, and the like.

Referring to FIG. 45, the vehicle 100 may include a communication unit110, a control unit 120, a memory unit 130, an input/output unit 140 a,and a positioning unit 140 b. Herein, blocks 110 to 130/140 a to 140 bcorrespond to block 110 to 130/140 of FIG. 42, respectively.

The communication unit 110 may transmit/receive signals (e.g., data,control signals, etc.) with other vehicles or external devices such as abase station. The control unit 120 may control components of the vehicle100 to perform various operations. The memory unit 130 may storedata/parameters/programs/codes/commands supporting various functions ofthe vehicle 100. The input/output unit 140 a may output an AR/VR objectbased on information in the memory unit 130. The input/output unit 140 amay include a HUD. The positioning unit 140 b may acquire positioninformation of the vehicle 100. The location information may includeabsolute location information of the vehicle 100, location informationwithin a driving line, acceleration information, location informationwith a neighboring vehicle, and the like. The positioning unit 140 b mayinclude a GPS and various sensors.

For example, the communication unit 110 of the vehicle 100 may receivemap information, traffic information, and the like from an externalserver and store it in the memory unit 130. The positioning unit 140 bmay obtain vehicle position information through GPS and various sensorsand store it in the memory unit 130. The control unit 120 may generate avirtual object based on map information, traffic information, vehiclelocation information, and the like, and the input/output unit 140 a maydisplay the generated virtual object on a window inside the vehicle(1410 and 1420). In addition, the control unit 120 may determine whetherthe vehicle 100 is normally operating within the driving line based onthe vehicle location information. When the vehicle 100 abnormallydeviates from the driving line, the control unit 120 may display awarning on the windshield of the vehicle through the input/output unit140 a. Also, the control unit 120 may broadcast a warning messageregarding the driving abnormality to surrounding vehicles through thecommunication unit 110. Depending on the situation, the control unit 120may transmit the location information of the vehicle and information ondriving/vehicle abnormality to the related organization through thecommunication unit 110.

FIG. 46 illustrates a XR device applied to the disclosure. The XR devicemay be implemented as an HMD, a head-up display (HUD) provided in avehicle, a television, a smartphone, a computer, a wearable device, ahome appliance, a digital signage, a vehicle, a robot, and the like.

Referring to FIG. 46, the XR device 100 a may include a communicationunit 110, a control unit 120, a memory unit 130, an input/output unit140 a, a sensor unit 140 b and a power supply unit 140 c. Herein, blocks110 to 130/140 a to 140 c correspond to blocks 110 to 130/140 in FIG.42.

The communication unit 110 may transmit/receive signals (e.g., mediadata, control signals, etc.) to/from external devices such as otherwireless devices, portable devices, or media servers. Media data mayinclude images, images, sounds, and the like. The control unit 120 maycontrol the components of the XR device 100 a to perform variousoperations. For example, the control unit 120 may be configured tocontrol and/or perform procedures such as video/image acquisition,(video/image) encoding, and metadata generation and processing. Thememory unit 130 may store data/parameters/programs/codes/commandsnecessary for driving the XR device 100 a/creating an XR object. Theinput/output unit 140 a may obtain control information, data, and thelike from the outside, and may output the generated XR object. Theinput/output unit 140 a may include a camera, a microphone, a user inputunit, a display unit, a speaker, and/or a haptic module. The sensor unit140 b may obtain an XR device state, surrounding environmentinformation, user information, and the like. The sensor unit 140 b mayinclude a proximity sensor, an illumination sensor, an accelerationsensor, a magnetic sensor, a gyro sensor, an inertial sensor, a RGBsensor, an IR sensor, a fingerprint recognition sensor, an ultrasonicsensor, an optical sensor, a microphone, and/or a radar. The powersupply unit 140 c supplies power to the XR device 100 a, and may includea wired/wireless charging circuit, a battery, and the like.

For example, the memory unit 130 of the XR device 100 a may includeinformation (e.g., data, etc.) necessary for generating an XR object(e.g., AR/VR/MR object). The input/output unit 140 a may obtain acommand to operate the XR device 100 a from the user, and the controlunit 120 may drive the XR device 100 a according to the user's drivingcommand. For example, when the user wants to watch a movie or newsthrough the XR device 100 a, the control unit 120 transmits the contentrequest information through the communication unit 130 to another device(e.g., the mobile device 100 b) or can be sent to the media server. Thecommunication unit 130 may download/stream contents such as movies andnews from another device (e.g., the portable device 100 b) or a mediaserver to the memory unit 130. The control unit 120 controls and/orperforms procedures such as video/image acquisition, (video/image)encoding, and metadata generation/processing for the content, and isacquired through the input/output unit 140 a/the sensor unit 140 b An XRobject can be generated/output based on information about onesurrounding space or a real object.

Also, the XR device 100 a is wirelessly connected to the portable device100 b through the communication unit 110, and the operation of the XRdevice 100 a may be controlled by the portable device 100 b. Forexample, the portable device 100 b may operate as a controller for theXR device 100 a. To this end, the XR device 100 a may obtain 3D locationinformation of the portable device 100 b, and then generate and outputan XR object corresponding to the portable device 100 b.

FIG. 47 illustrates a robot applied to the disclosure. The robot may beclassified into industrial, medical, home, military, and the likedepending on the purpose or field of use.

Referring to FIG. 47, the robot 100 may include a communication unit110, a control unit 120, a memory unit 130, an input/output unit 140 a,a sensor unit 140 b, and a driving unit 140 c. Herein, blocks 110 to130/140 a to 140 c correspond to blocks 110 to 130/140 in FIG. 42.

The communication unit 110 may transmit/receive signals (e.g., drivinginformation, control signal, etc.) to/from external device such as otherwireless device, other robot, or a control server. The control unit 120may perform various operations by controlling the components of therobot 100. The memory unit 130 may storedata/parameters/programs/codes/commands supporting various functions ofthe robot 100. The input/output unit 140 a may obtain information fromthe outside of the robot 100 and may output information to the outsideof the robot 100. The input/output unit 140 a may include a camera, amicrophone, an user input unit, a display unit, a speaker, and/or ahaptic module, etc. The sensor unit 140 b may obtain internalinformation, surrounding environment information, user information andthe like of the robot 100. The sensor unit may include a proximitysensor, an illumination sensor, an acceleration sensor, a magneticsensor, a gyro sensor, an inertial sensor, an IR sensor, a fingerprintrecognition sensor, an ultrasonic sensor, an optical sensor, amicrophone, a radar, and the like. The driving unit 140 c may performvarious physical operations such as moving a robot joint. In addition,the driving unit 140 c may make the robot 100 travel on the ground orfly in the air. The driving unit 140 c may include an actuator, a motor,a wheel, a brake, a propeller, and the like.

FIG. 48 illustrates an AI device applied to the disclosure. The AIdevice may be implemented as a stationary device or a mobile device,such as a TV, a projector, a smartphone, a PC, a laptop, a digitalbroadcasting terminal, a tablet PC, a wearable device, a set-top box, aradio, a washing machine, a refrigerator, digital signage, a robot, anda vehicle.

Referring to FIG. 48, the AI device 100 may include a communication unit110, a control unit 120, a memory unit 130, an input unit 140 a, anoutput unit 140 b, a learning processor unit 140 c, and a sensor unit140 d. Blocks 110 to 130/140 a to 140 d correspond to the blocks 110 to130/140 of FIG. 42, respectively.

The communication unit 110 may transmit and receive wired or wirelesssignals (e.g., sensor information, a user input, a learning mode, acontrol signal, or the like) to and from external devices, a differentAI device (e.g., 100 x, 200, or 400 in FIG. 39) or an AI server (e.g.,400 in FIG. 39) using wired or wireless communication technologies. Tothis end, the communication unit 110 may transmit information in thememory unit 130 to an external device or may transmit a signal receivedfrom the external device to the memory unit 130.

The control unit 120 may determine at least one executable operation ofthe AI device 100 on the basis of information determined or generatedusing a data analysis algorithm or a machine-learning algorithm. Thecontrol unit 120 may control components of the AI device 100 to performthe determined operation. For example, the control unit 120 may request,retrieve, receive, or utilize data of the learning processor unit 140 cor the memory unit 130 and may control components of the AI device 100to perform a predicted operation or an operation determined to bepreferable among the at least one executable operation. The control unit120 may collect history information including details about an operationof the AI device 100 or a user's feedback on the operation and may storethe history information in the memory unit 130 or the learning processorunit 140 c or may transmit the history information to an externaldevice, such as the AI server (400 in FIG. 39). The collected historyinformation may be used to update a learning model.

The memory unit 130 may store data for supporting various functions ofthe AI device 100. For example, the memory unit 130 may store dataobtained from the input unit 140 a, data obtained from the communicationunit 110, output data from the learning processor unit 140 c, and dataobtained from the sensing unit 140. Further, the memory unit 130 maystore control information and/or a software code necessary for theoperation/execution of the control unit 120.

The input unit 140 a may obtain various types of data from the outsideof the AI device 100. For example, the input unit 140 a may obtainlearning data for model learning and input data to which a learningmodel is applied. The input unit 140 a may include a camera, amicrophone, and/or a user input unit. The output unit 140 b may generatevisual, auditory, or tactile output. The output unit 140 b may include adisplay unit, a speaker, and/or a haptic module. The sensing unit 140may obtain at least one of internal information about the AI device 100,environmental information about the AI device 100, and user informationusing various sensors. The sensing unit 140 may include a proximitysensor, an illuminance sensor, an acceleration sensor, a magneticsensor, a gyro sensor, an inertial sensor, an RGB sensor, an IR sensor,a fingerprint sensor, an ultrasonic sensor, an optical sensor, amicrophone, and/or a radar.

The learning processor unit 140 c may train a model including artificialneural networks using learning data. The learning processor unit 140 cmay perform AI processing together with a learning processor unit of anAI server (400 in FIG. 39). The learning processor unit 140 c mayprocess information received from an external device through thecommunication unit 110 and/or information stored in the memory unit 130.In addition, an output value from the learning processor unit 140 c maybe transmitted to an external device through the communication unit 110and/or may be stored in the memory unit 130.

What is claimed is:
 1. A synchronization method for a distributed unit(DU) transmission timing performed by an integrated access and backhaul(IAB) node in a wireless communication system, the method comprising:transmitting a random access preamble to a parent node; receiving arandom access response from the parent node; receiving a first parameterrelated to a mobile termination (MT) transmission timing of the IAB nodeand a second parameter related to the DU transmission timing of the IABnode from the parent node; determining a time spacing between an MTreception timing and the DU transmission timing of the IAB node based onthe first parameter and the second parameter; and performingsynchronization for the DU transmission timing with the parent nodebased on the time spacing.
 2. The method of claim 1, wherein anidentical DU transmission timing is set to multiple nodes included inthe IAB system for the synchronization.
 3. The method of claim 1,wherein the MT transmission timing and the MT reception timing aretimings related to operations between the IAB node and the parent node,and wherein the DU transmission timing is a timing related to anoperation between a child node of the IAB node and the IAB node.
 4. Themethod of claim 1, wherein the first parameter and the second parameterare independently transmitted with each other.
 5. The method of claim 1,wherein the first parameter is transmitted using a timing advance (TA)command signal.
 6. The method of claim 1, wherein the first parameterand the second parameter are included in a single signal andtransmitted.
 7. The method of claim 1, wherein the DU transmissiontiming is determined based on a summation of the first parameter and thesecond parameter.
 8. The method of claim 1, wherein the IAB nodereceives each of the first parameter and the second parameter formultiple times, and wherein the DU transmission timing is determinedbased on a filtered value from each of the first parameter and thesecond parameter.
 9. The method of claim 8, wherein the filtered valueis an average value.
 10. The method of claim 8, wherein the filteredvalue is a value determined based on values of a parameter transmittedby the parent node or a value determined based on values of a parameterreceived by the IAB node.
 11. The method of claim 8, wherein the IABnode receives filtering information for the filtering from the parentnode, and wherein the filtering information informs at least one of acoefficient used for the filtering or a window size to which thefiltering is applied.
 12. The method of claim 1, wherein the firstparameter and the second parameter are independently transmitted. 13.The method of claim 1, wherein the IAB node transmits report informationto the parent node, and wherein the report information includesinformation related to the timing spacing.
 14. The method of claim 13,wherein the report information informs the first parameter.
 15. Themethod of claim 1, wherein the second parameter is transmitted through amedium access control-control element (MAC-CE) signaling.
 16. A nodecomprising: one or more memories storing instructions; one or moretransceivers; and one or more processors connecting the one or morememories with the one or more transceivers, wherein the one or moreprocessors, by executing the instruction, are configured to perform:transmitting a random access preamble to a parent node; receiving arandom access response from the parent node; receiving a first parameterrelated to a mobile termination (MT) transmission timing of anintegrated access and backhaul (IAB) node and a second parameter relatedto a distributed unit (DU) transmission timing of the IAB node from theparent node; determining a time spacing between an MT reception timingand the DU transmission timing of the IAB node based on the firstparameter and the second parameter; and performing synchronization forthe DU transmission timing with the parent node based on the timespacing.
 17. The node of claim 16, wherein the IAB node communicateswith at least one of a mobile terminal, a network, or an autonomousdriving vehicle except the node.
 18. The node of claim 16, wherein theIAB node is a base station or a user equipment.
 19. An apparatusconfigured to control an integrated access and backhaul (IAB) node,comprising: one or more processors; and one or more memories workablyconnected to the one or more processors and store instructions, whereinthe one or more processors, by executing the instruction, are configuredto perform; transmitting a random access preamble to a parent node;receiving a random access response from the parent node; receiving afirst parameter related to a mobile termination (MT) transmission timingof the IAB node and a second parameter related to a distributed unit DU)transmission timing of the IAB node from the parent node; determining atime spacing between an MT reception timing and the DU transmissiontiming of the IAB node based on the first parameter and the secondparameter; and performing synchronization for the DU transmission timingwith the parent node based on the time spacing.